first thing that costs nowt – flip the stem, play about with the bar angle, rearrange the spacers so the bars come up. Then you can slowly drop them a bit at a time until you find the right bar height and position
second thing, do some regular stretching, before and after the ride – again costs nowt
[edit: keep remembering things] don’t grip the bars too tightly, bend the elbows. hoods aren’t for riding long stretches on, use all the different hand positions as that’s why they are shaped like that, for variety
something that costs very little – double wrap the bars, simply put a second layer of bartape on top of the first, cost about a tenner
also, fresh pair of gloves as they compress over time and lose the padding (prendas knock out really good ones for much less than the high street prices)