These hints are more-or-less in chronological order. If you're trying to solve a puzzle without first dealing with the problem addressed BEFORE it in this list, the hint will not work.

How do I get out of the truck?

What do I do about the dog?

So how do I get rid of the guard by the Jeep?

How do I fill the Jeep's tank?

I can't get past the soldier by the truck.

Okay, an empty gas can's not going to get me anywhere. How do I fill it?