Climb more overhangs, basically. Best way to do that in a structured way is to spend more time bouldering. Get on the steepest boulders you can handle. The easier the better, because what you want to do is be able to run multiple laps in order to fine tune your beta and figure out how to flow.

Also, fact of the matter is that you need to be stronger to climb overhung stuff. Keep your core VERY tight and don't let your ass droop. Forearms should be rightly in line with gravity and your shoulders pulled back so that your back muscles are doing the heavy lifting. Think a lot about your feet. Every foot placement should be doing something for you beyond just providing a way to push upward. Pulling or balancing or whatever.

And while being "in balance" is an obvious requirement on slabs, it's just as important on an overhang. Maybe even more important. With rare exceptions, every move should be completely controlled by being in balance. When you take a hand off the wall to make a move, your body should remain rock solid and locked in place on 3 (sometimes two) points. Usually that means keeping your feet on either side of your hand so you're stable. Usually that means moving your feet more often than are.

For me, cracking into the V5+ and steep 5.11-5.12 stuff was 100% about footwork. Probably 90% of the time when I'm failing to send due to pump, the solution is to slow down, breathe more and focus on keeping those feet in the perfect spot. Good climbers move their feet twice as often as intermediate climbers and probably 4x as often as newbies.