Head straight across the little camp fire area (you may hear some bear noises) and start walking along the path to where you'll see a Psi-Card up to your left a ways down. Hop the fence and grab it, up a bit higher is the bear (the one the kid in Camp was talking about if you spoke with him). You're not going to be able to do much damage to the bear yet, so I wouldn't try too hard, but there is another Psi-Card up in his area if you run and avoid him you can pick up and then head back to the path and continue on.
The path leads to an area with some steps leading up and also to the right, up the steps is a little trailer home that appears to be Ford Cruller's. Back and to the right of this open area is a rock you can jump on by a tree, jump up on the rock then look over to the tree and you can see there is a tight rope connected to the tree. So jump up there and head across the rope where you'll pick up one Psi-Card right away and another on the other end.
Jump off here in the direction back by where you came and you'll see a UTS tree trunk and a little cave area with a Psi-Card in the entrance. Grab the Psi-Card but don't enter the cave because this appears to be Mr. Bear's home and he doesn't exactly want you in here. From the cave head back toward the path, but instead of getting on it go straight through the opening where there is kind of an "unofficial path."
Heading down here you'll come to a sort of "pride rock" on your left, go up on the land on the right of it, then up on to it two jumps, then you can jump to some land on the other side of it, from here you can jump back on top of it for a Psi-Card. Then you can turn around and jump up on a little piece of the big tree there, then up on to one of the branches with another Psi-Card. Going in the same direction jump off the tree toward some more rocks with a Psi-Card on the left. You're now right above the tight rope we walked in Cruller's little area.
Don't jump back down on the path yet, stay up here and get on top of pride rock again. You'll notice there are some more rocks behind it you can jump onto, from there jump away from the big tree as far as you can and you may have to do some more jumping when you land, but you'll find that there is an area back here with a full Psi-Challenge Marker. Since you can't see it when you jump it may take you a jump to find it then another to get it, it's there though, I swear.
Straight out of this little area is a wooden log with another Psi-Card. We can see two more cards in sight from here, one straight ahead and one to the left, it doesn't seem like we can quite make it to the one out straight yet, so we'll come back. But head over and grab the one to the left which actually is surrounded by more climbable rocks, if we go up a little to the left of this card we'll see another card out in front of us. Now if we jump down in the direction of this waterfall and stay on the left side we'll come to yet another Psi-Card. Directly to the right of us now, across the water, is even another.
Now you can work your way up this area you're on where there is another Psi-Card at the top. Now jump down to where the big bridge is and head into GPC and Wilderness.