My typing teacher used these little cardboard cutouts that stood above the keyboard so you couldn't see the keys. These kept you honest. After that we just used some ancient DOS typing software that started you out typing strings of random letters composed of the homerow. As time went on it started introducing keys from the other two rows as well as numbers.

It was frustrating at first because of how slow I became at something I was normally fast at. However, in the long run my speed more than doubled once I learned how to touch type properly.