Can you please give a link to that site?

My tip to improve your typing speed is to practice common words. For example, there are many words that have "tion" endings. When you can get the flow of being able to type that part, you'll type out that ending using pure muscle memory. This concept can be applied to all words essentially.

What really helped me improve my typing speed was surprisingly playing really difficult songs on a game called Flash Flash Revolution. That was the start of it at least...

When my fingers hurt after too much time on the keyboard, I take a break. It's always good to take a break every 2 hours for about 15 minutes.