Whatever sounds best!
With hi hats & cymbals I don't like them to sound too harsh. I roll off the bottom until I hear them as a distinct layer, then boost that a little.
EQ is one of those things you need to keep re-adjusting as you build up the track, so it best not to have too many rules at the start. You might end up with a bassline & a kick that get in each other's way if they both have the low end boosted. You might then find that cutting the bottom out of that kick so it is more of a mid-range punch is better.
