I think I spend more time feeling the body than actually working on it; my hands are one of my main diagnostic tools for alerting me to issues and a pretty sensitive one at that. And then guidecoat, as Tech also says.
I did some paint and body school for ****s n giggles because I was militant about the hobby and since then have had several years developing my craft on this car so it's not like I'm a complete novice. But skim coating is something I had little practice at and I'm feeling better about it after all the good advice. Cutting sooner and with a more aggressive grit are going to be the two singlemost things to help me I think, and I need to start mixing my filler on a bigger pallete too so I can mix more; right now I'm just using my 11x11 pallete with tear away sheets and I remember tech69 saying before he doesn't like them because they're too small.