My tip to improve your typing speed is to... slow down and work on your accuracy. Even though it feels amazing to let your fingers fly across the keyboard. If your accuracy sucks, your speed will suck as well. So slow down your speed, and just focus on your accuracy. If your accuracy is high, then your speed as well will increase. Less mistakes means that you can type quicker.

What really helped me improve my typing speed is... that if you first work on improving your accuracy, by starting slow and then speeding it up, then your speed will improve as well.