For hills, I've always tried to maintain a good spin (full-circles) in a lower gear, & only worry about myself (not a racer). Later techniques I learned for longer hills:
-Once the spin is used up in almost the lowest gear, I can either add more leg force using the lower back of my seat as a brace (like a leg-lift weight machine).
-I can pull on the handle bars, forcing my weight & legs forward on the pedals.
t really depends on which bent I'm on and how it's configured. EZ-1 is a handlebar puller, the tadpole trike is a leg-press.
I enjoy hill challenges on my bents. The Ez-1 with a 20" wheel is better than you'd think, and on the trike, well... I don't have to worry about tipping over, LOL! I've ridden past many mtn/road bikers that were walking on steep grades, but a few times on my trike found myself thinking, 'I could walk this hill faster' as I chugged up the hill pressing each leg one after the other.
I guess, just ride more & they'll get easier! Happy trails!