What really helped me improve my typing speed is, in addition to practice, knowing correct finger positioning on the keyboard. This helps touch typing immensely. (I use a Qwerty keyboard.)

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

What really helped me improve my typing speed is... practice, practice, practice.

When my fingers hurt after too much time on the keyboard, I... step away from the keyboard and computer. I stretch my wrists and hands with ergonomic exercises I've been taught.