I know a lot of people will recommend something harsher and more toxic that plain old neem, but I've tackled them with just neem before. The thing is... when you think you've got the bastards, I'd recommend that you continue treating your plants. It may seem that the mites are all gone, but the neem will do nothing to the eggs sitting on your leaves, and most likely you're going to see mites popping up again in a week. What worked for me was to spray neem very thoroughly every three days, and repeating that four times.