There are some really great achievement guides out there, and I even used some to figure out good places to do some of these. I did not copy and paste any of their strategies and I do not intend to take credit for their ideas. After completing all of these achievements (except the survivor mode ones) I am giving my opinion on them.
xbox360achievements.org is a great place to get more info on achievements and talk in the forums with people who are constantly achievement hunting and giving great advice. I recommend you check it out yourself.
Dead Rising's achievements are each worth 20 gamerpoints, for a total of 1000.
3 Day Survivor — Simply survive all 3 days of 72 hour mode.
5 Day Survivor — See 7 Day Survivor.
7 Day Survivor — For this you must play Survival mode. This mode is a bit different from the regular mode — there is no way to save, so when you die the game ends. Food does not respawn, so you will have to conserve only when needed. Your life is constantly draining the whole time, so you cannot just stand around. Defeating Psychopaths will leave behind boxes of food/weapons. This is not easy and takes 14 hours of straight Dead Rising action.
Bullet Point — Fire 1,000 bullets in 1 playthrough. Just keep firing shots — fire off some sub-machine guns and you'll have this in no time.
Carjacker — Steal the Convicts' car. Once you've defeated the Convicts, jump in their car to drive it around.
Census Taker — Photograph 50 survivors. This achievement is a major reason for me writing this guide, so follow it to obtain this! There are 53 possible survivors, so getting this requires all but 3 of them.
Clothes Horse — Try on every piece of clothing in the mall. The easiest way to do this is to just go in every store and try on everything you can. The unlockable outfits do not count towards this achievement.
Costume Party — Place novelty masks on at least 10 zombies. Inside Child's Play in Paradise Plaza are the Lego heads — grab these and place them on zombies, and after 10 you'll get this achievement.
Frank the Pimp — Escort 8 female survivors at the same time. This is one of the trickiest achievements in the game — look up a step-by-step guide for it on xbox360achievements.org. I followed that to get it myself, so there's really no point writing it up again here.
Freefall — Drop from a height of at least 16 feet. You can get this by jumping off any second floor area down to the first floor, such as from Columbian Roastmasters in Paradise Plaza or off the Space Ride in Wonderland.
Full Set — Collect all portraits in the notebook. This does not mean you need a photo of everyone in the game — you just need to meet them once. This also does not need to be done in one playthrough — it is cumulative over every time you play the game. But if you just follow this guide you will get this in one playthrough.
Gourmet — Eat one of every type of food in the mall (in one playthrough). Most everything you need can be found in Seon's grocery store in the North Plaza, but you will also need to drink the mixed drinks and eat the pie in Columbian Roastmasters. I don't have all the mixes off-hand, but a quick search will find them easily enough.
Group Photo — Get 50 target markers in one photo. Honestly, you can probably do this right at the beginning when the zombies first enter the mall. But the easiest place would be to just go to the Maintenance Tunnels and take a photo there.
Hella Copter — Shoot down a helicopter. On the 4th day with ending A (meaning you've done all the story cases), a helicopter will show up in Leisure Park. There are two ways to take it down: use a Sniper Rifle (get from the Huntin' Shack) to shoot the pilot, or use a Machine Gun (get from any Special-Ops soldier) to shoot the tail of the chopper. I was pretty bad at both, but through persistence and frustration I did get it down — search up some videos if you're having trouble.
Humanist — Get at least 10 survivors out of the mall. Simply save 10 people — if you are getting ending B you automatically get Jessie, Ed, Barnaby (depending on the number of cases you complete), Otis, and Frank. So you really only need to find 5 others in the mall.
Indoorsman — Stay indoors for 24 consecutive hours. Yes, you can just sit in the Security Room for 24 hours (2 real-time hours).
Item Smasher — Break 100 items. Just by playing through the game there's a 99% chance you'll get this achievement. If you don't, just go break some potted plants, cash registers, TVs, windows, or whatever.
Karate Champ — Defeat 1,000 enemies barehanded. Sounds a lot worse than it is. You'll definitely want to be level 50 when you go for this, though. The best way I found to do it was to go down into the Maintenance Tunnels by Paradise Plaza (this means having the Maintenance Tunnels key already so you can use the door there) and use Frank's Double Lariat move (hold the left stick button and press X) — you'll get several kills with each one. Just keep doing it over and over. Since you're right by Paradise Plaza, anytime you take too much damage you can just head up to Columbian Roastmasters and grab some Orange Juice, and save in the bathrooms.
Legendary Soldier — Defeat at least 10 Special Forces. With your chainsaw or the Mega-Buster you'll have this in no time. If you don't have either, just grab some shotguns or sniper rifles and after you kill one of these dudes, snag their machine gun.
Level Max — Reach Level 50. Won't take any time at all saving survivors — dedicate a playthrough to leveling up and saving survivors to get yourself familiar with the mall and scoops. You'll be glad you did.
Life Saver — Get at least 20 survivors out of the mall. This guide gets you 50-53 out (depending on your ending), so just follow it.
Marathon Runner — Cover a distance of 26.2 miles. This achievement totals up all of the times you've played the game, so you'll get it eventually. If you want to speed up how quickly you get it, just keep running into a wall whenever you have nothing else to do.
Outdoorsman — Spend 24 consecutive hours outdoors. You can get this achievement by just standing on the heli-pad for 24 hours (2 real-time hours), or if you choose to, after acquiring Indoorsman simply save your game, turn off your console, turn it back on, and Outdoorsman will unlock. I've read this can mess your save up if you're at a certain point or something, but it worked fine for me.
Overtime Mode — Do all cases and be at the heli-port at noon on the last day, which will take you into Overtime mode and unlock this.
Peace Keeper — Defeat at least 5 Psychopaths. There are 12 total in the game, so getting 5 of them isn't too tough.
Perfect Gunner — Don't miss with a machine gun. First off, sub-machine guns don't count for this. You have to get a Machine Gun off of a Special Forces soldier towards the end of the game and fire all 150 shots without missing. If you want an easy way to do it, take one into the Maintenance Tunnels into the butcher shop and fire the entire thing at one of the hanging cows, and you'll get this.
Photojournalist — Score at least 1,500 PP from any photo. If you watch survivors/Psychopaths, sometimes they get a "PP" symbol over their head. Take a picture of one of them when this appears and you'll score way more than 1500 points.
Portraiture — Photograph at least 10 survivors. If you're saving them, just remember to take some pictures of them. If you forget anyone, you can go in the Security Room where they are located and get your photos there.
PP Collector — Photograph all PP stickers throughout the mall. There are several teeny tiny PP markers on certain objects in the mall — you need to photograph all of them. For example, there is one on the bulletin board above the bench you can save on in the Security Room. You'll also notice when you go to take a picture of one, a PP percentage will appear on the bottom of the screen. So you can either go around the mall looking at objects through your lens to find them, or just read a guide somewhere — I don't have them all listed off-hand.
Psycho Collector — Photograph at least 10 Psychopaths. There are 12 total, so when you kill them make sure you photograph them. Most can be photographed after they are dead — the main exception to this is Paul, who becomes a survivor after you "defeat" him.
Psycho Photo — Photograph at least 4 Psychopaths. See Psycho Collector above.
Punisher — Defeat at least 10 Psychopaths. As Psycho Collector states, there are 12 Psychopaths total and you can defeat all of them in one playthrough, so just do it.
Raining Zombies — Knock at least 30 zombies aside with a parasol. In the Entrance Plaza and in Al Fresco Plaza there are plenty of parasols stuck in the ground. Simply grab one and hold down X to position it in front of you, then run into 30 zombies! It's fun!
Saint — Save 50 survivors. This is half of the reason I wrote this guide, so follow it and you will successfully get 53 survivors out of the mall! However, if you do all the cases you'll need to complete Overtime mode, and you'll actually end up with 50 survivors. Ending B is how you can get 53, and it's the only way.
Self Defense — Defeat at least 1 Psychopath. If you are playing the storyline you'll get this automatically when you defeat Steven, but any Psycho will count for this.
Sharp Dresser — Change into at least 20 different costumes. I don't know if unlockables count towards this, but just change into 20 different clothing items over all your playthroughs.
Snuff Shot B — Take a picture of zombie Brad. Occurs during the main story after you collect the bombs — go back to the room where the Maintenance Tunnels key is and you'll get a scene and find Brad as a zombie. Photo him.
Snuff Shot J — Take a picture of Jessie as a zombie. You'll get a scene where you see her turn — head back to the Security Room and she'll be stumbling around. Take a photo of her.
Strike! — Knock over 10 zombies with one bowling ball. Bowling balls can be found at the sports store in Paradise Plaza (and probably some of the other sports stores, but this is an easy place) — grab one and head into the Maintenance Tunnels, hold R and aim at a big cluster, hold in X to wind up real good, and let it go. You have a 99% chance of hitting at least 10 zombies easy.
Stunt Driver — Jump a car at least 33 feet. There is a red sports car over by where you enter the Maintenance Tunnels. Grab this and head into Leisure Park — going pretty quick and hitting the edge of the small pond in front of the Food Court should get this. There are several strategies for it online too.
Stunt Rider — Get the motorcycle by the entrance to the Maintenance Tunnels, drive it up to the top of the stairs by the entrance to the North Plaza, and drive it off the left side. This takes some work and positioning, and it helps to clear out the zombies first so you have a good view, but going at decent speed and missing the railing should jump you off.
The Artiste — Score at least 3,000 PP from a single photo. Like Photojournalist, just take a picture of any of the survivors while the "PP" symbol is above them and you'll score more than enough points.
Tour Guide — Escort 8 survivors at once. There's actually a point in this guide where you'll have 8 people going, which will get this for you. Otherwise it will take a playthrough dedicated to Frank the Pimp to get that, which will have you with 8 people, so it's probably worth just doing that.
Transmissionary — Answer all of Otis' calls. This is the other half (the first being Saint) of why I wrote this guide, so just follow it — the calls can be a bit tricky and annoying.
Unbreakable — Get the true ending without being knocked out. In Overtime mode, if you get "killed" at any time you'll find yourself tied up with the Special Forces — this means you didn't die, but were "knocked out." So either don't die during Overtime mode, or reload if you do; when you beat it you'll get this.
Zombie Genocider — Defeat at least 53,594 zombies in one playthrough. This is a lot of zombie killing and you will not get it without spending an entire playthrough going just for this. It takes about 2 straight game days of driving around the Maintenance Tunnels. But it does come with a great reward — the Real Mega-Buster! The path you take when driving is something best figured out for yourself — drive around, test out how long each car can last and where the most zombies are, and you'll get a feel for it.
Zombie Hunter — Defeat 1,000 zombies. You will do this easily in a normal playthrough.
Zombie Killer — Defeat 10,000 zombies. You could do this pretty easily in a playthrough, but there's not much point going for this if you're not just going to go for Genocider.
Zombie Road — Walk over 33 feet on the backs of zombies using the skill called Zombie Walk. Zombie Walk is fun, and this doesn't have to be a consecutive 33 feet — just 33 feet total, so you'll get it easily just figuring out how to zombie walk.
