I try to always do a "round-robin" pre-flight check before taking off on a new project. Headset snug? Check. Stem seated? Check. Quick release tightened? Check. You know the score from there. I think all of us have had a brain fart at one time or another that led to a frightening sudden realization that the handlebars were loose or the brakes not adjusted. I'll also ride pretty gingerly for the first couple of times out, just in case. Up and down the block at first, until I'm confident I won't experience a Three Stooges moment further abroad and down the road.
I'm fortunate not to have had too many mishaps, and those seem to have come about when I was just getting overconfident. For instance, I recently had a chain break about seven miles from home. No worries, I'll pull out my handy chain tool and spare link and... uh oh... those are in a different bike bag... at home.
It was a long walk back.