What really helped me improve my typing speed is not actually thinking about speed but by thinking about accuracy. At first I used to type very fast and my only thought was to type as fast as I could. But later after two three days I started realizing that the lesser I made mistakes the more I was I able to type fast. Yes! It worked I started to learn typing very slow and try to get fully accurate every single time and slowly unknowingly I was increasing my speed also.