Make friends with the yard owner. Unless you have a fully loaded equipment type service truck with air and torches, this usually helps more than anything else...
I'll second that. Visited one up west of Austin a while back. Talked to the guy about cars for a bit and he almost pulled our parts for us. Well, he let us borrow damn near a whole toolbox, and a sawzall, but yeah, that old honey and vinegar saying has merit.
