Type to the beat of a song. Start with a slow beat and work your way up. Don't rush it. Typing in bursts is often counter productive. Rhythm causes accuracy. The keyboard is just like a musical instrument and that's how musicians gain accuracy. You also need to practice regularly, even if just for 5 mins each day, to train your muscles.
I forget the details, but I remember the following was asked of some famous violinist:
"How did you learn to play so fast?"
His reply: "Really, really slowly".
:)