Tips, tricks, experience learning to play without watching the fretboard.

I've been playing several years now and can get around well enough on most of the songs I've wanted to play. But my experience has not been gigging or playing while standing... just sitting around with friends, or practicing. In that environment, it's easy enough to watch what's going on on the fretboard while playing, except while singing. Any tips/suggestions for how best to free up your head/eyes while still playing accurately?