TL;DR: grip the bar across the joint at the bottom of your fingers instead of across the middle of your palm. This doesn't apply to bench pressing (a push), but applies to all moves that involve pulling/lifting the bar.
I don't know, maybe I'll try this next time I deadlift but I feel like it would just weaken my already weak grip.
Grip is the main way we interact with the world, so it's worth training it. Also, grip strength is the most reliable predictor we have found for life expectancy. (i.e. higher grip strength means higher life expectancy). It could be correlation/causation fallacy, but I have decided to just assume it's worth training it for all the other benefits that having good grip strength brings.
Where can I read more about the techniques and/or bad habits? Interesting.