Here we go, a very crude drawing of what I build on a typical trip. The left is what I build most of the time, served me well both with and without a tarp. I typically make the channel about 18cm deep all the way around, and dig it out to the nearest incline so gravity can take effect.
The second is what I build if I'm within 25-30 feet of a body of water, with minimal incline between me and the water. The point is to get your body off the ground, so that bugs and the like don't mess with you all night, and to keep water from catching you in your sleep. The hardest part, more often than not, is getting the lower frame to stay tightly bound to the other branches. With this setup you can avoid waking up underwater. Obviously this is a very bad diagram, but the point is to get the idea across.
These are really the only two shelters I build, since they can be improved upon regularly. Sometimes I put flat stones on the tops and sides to keep the foliage from blowing away when its overly windy.
The pit pit in the bottom has a name, I forgot what it was, but its great for cooking. Dig a little ground bridge and make it nice and clear underneath. Then, add tinder to one side, as well as some wood, then light it up. What happens is as the heat rises, it draws in air from the other side of the hole, creating far less smoke, and a far hotter fire. Since it's part way underground, all you would really have to do is put down a nice flat stone or metal grate and plop your meat on it. It's also very easy to put out, since you can fill the hole with the dirt you dug or fill it with water.
I'm by no means an expert, just a hobbyist throwing some things out there that have worked for me.
