The easiest way to get a GOOD stand that I now of is this. Find four trees in a square or close to square pattern. Run planks or whatever your using depending on the size of the square from each one in a square again. Now just lay more planks over these and nail them down for something to stand on. Then just build yourself a ladder and your set. If you want you can put some supports under it but thats not usually necessary.

If you cant find four trees in this pattern, 3 in a triangle will work also.