My tip to improve your typing speed is to slow down and focus on improving your accuracy. When I do this, I find I usually score a higher score than when I'm trying to type for speed.

What really helped me improve my typing speed was when I painted my keyboard black. This broke me of the habit of glancing at my hands while typing and forced me to memorize the where all of the keys were. It took a litlte bit of time to get used to, but in the long run it has helped me out a lot.