So I'm going to attempt to build an 18' section of fence and I'm looking for some advice. What to avoid and that kind of thing. My plan is to put in 3 pressure treated 4x4's at 6' intervals. I was going to dig the holes about 2' deep, but someone else told me to go 3' deep and layer the bottom with about 6" of gravel for water run off? Sound OK so far? I was also going to go with those brackets you can buy for Lowes for the backing and then just nail up the cedar planks? Any tips?