hhmmm... I prefer biros, not gel pens. but maybe i just haven't come by good ones.
anyway, I have three pointers.
firstly, don't grip hard. practice writing pressing lightly. Less pressure, quicker and smoother writing.
secondly, I use a range of pens with different sized grips. sometimes its just nice to have a different thickness of pens.
lastly, running writing, that is, if you don't do this already.
best of luck.
i used to think I would never have this problem, ever. But then suddenly I felt a bit of pain in my right hand very randomly. Not anymore, but now I understand that writing essays can be a problem for some people.