When my fingers hurt after too much time on the keyboard, I do nothing, I will simply take some rest or go outside because we should not do continuous work because we will be stressed, so I will take some time to allow rest to my fingers

My tip to improve your typing speed is to type slowly and accurately, just focus on accuracy and your typing speed will become faster than before. If you try to type faster and make mistakes than your time will go to correct mistakes and it will decrease your typing speed and accuracy, so type slowly and accurately. Just remember one thing typing speed will increase only with practicing typing accurately.