Outside: I start at 20 yds. because this is the maximum distance that I feel comfortable shooting at a deer. I will move back to 30 yds. and shoot for a while, but finish my shooting at 20.
Inside: I shoot 18 yds. Before and during deer season, I'll also shoot at a block target with the silhouette of a deer's kill area. This really helps me to place the arrow in the kill zone, as with shooting a 3D deer target outside. I often stump shoot with friends at all kinds of yardage, which really helps my overall shooting (form and getting the feel of my bow).