So foraging is pretty simple. Basically you pretend you're an Indian and go hunting for nuts and berries. However, there are some rules that will make things a lot easier.
1. PLEASE please please know what you are picking and make sure it's not poisonous. I stick with plants that are easily recognizable, many of which I have been familiar with since childhood.
2. Don't go foraging where you're not wanted. I try to stay around our property/rented property and in more-or-less public ditches. I live in the country so this is not an issue and I find a ton of stuff. However, if you're going to be traipsing through someone's private woods, at least ask permission so they know what you're doing. And maybe avoid hunting season...
3. Don't get lost. Another reason why I like ditches and public roads.
One thing to keep in mind is that foraging can be done all year (I mean, native Americans did it, right?). Spring is better for foraging salad greens, while fall will get you a lot more nuts and berries.
Those are the basic guidelines. Foraging trips usually lasts an hour or less; I don't go if it's raining or storming. It would be a good idea to wear pants to protect from thorns. I wear grubby tennis shoes because many times they come back with mud and burrs on them. For transportation I use a bike, and have all tools and supplies conveniently packed in my foraging bag, which we'll look into next time.