Learn really easy songs and build up.
The most important thing I've learned as a musician is always start stuff slow. If you just start playing stuff fast, you won't get better and you'll play extremely sloppy.
For example, I'm teaching myself to sweep pick on my guitar and I play like two notes a second just so I can get the technique down so that when I start going faster it will sound really good. It's boring as hell but it's really important.