When my fingers hurt after too much time on the keyboard, I... take a quick break and stretch/shake out, because at that point I make way too many errors to be efficient when typing, and I need to slow my brain down to the speed of my fingers to avoid making so many mistakes.

This is the tracking of my progress through my Colemak learning experience. The goal is 100 WPM and 95%+ accuracy.

My tip to improve your typing speed is to...

Try a more efficient touch typing layout, and when learning it make sure to delete the entire word when making a typo and start again to avoid reinforcing bad habits.