Lots of things to consider really – just basic things like rotation of the bars / how hard you are gripping the bars – are you tending up too much etc / are your forks setup as good as they could be / tyre pressures too hard / are you in a good position on the bike? All these things you can play with (one adjustment at a time) are free.
After that you could try new grips – are the ones you have too thin or too fat to be comfortable? I’ve settled on Raceface half nelsons which are quite thin – I tried some fatter uberbike and Nukeproof Sam Hill’s but I found they were too big and made things worse.
In terms of tyre pressures I’m now down to 20 psi ish at the front and 25 at the rear – I never go lower but occasionally go higher if I’m going somewhere where I’m worried about pinch flats / denting rims. Generally it gives you an easier time and more grip to run lower pressures.
I found one handlebar I had made me feel uncomfy on the bike – it wasn’t a cheap one (Raceface Aeffect) – and I concluded it didn’t have enough sweep so my hands felt too ‘straight’ on the bars. I picked up a Planet X el guapo which is actually a cheaper bar but had more back and up sweep and I’m much happier on that.
Another small thing, but what angl ehave you got your brake levers at? I always had them about 45 degrees down from parallel with the ground but as I’ve ridden steeper and faster terrain I’ve rotated them back a bit closer to parallel – which stops you being so twisted over the front of the bar. Not a huge adjustment but it made a difference.