The opinion I always have is that anybody should start with an acoustic - not an electric or a classic. There are several reasons for that - the first being that the acoustic is the hardest to play. Well, maybe you'll disagree with me, but it's harder than the electric due to how far the strings are from the neck, and it's harder the the classic for obvious reasons. The fact that it's harder to play might sound like a stupid reason for buying it, but the reasoning for this is that if you can play the acoustic, you should have no trouble if you plan on switching to an electric or even a classic. Secondly, when you're first playing the guitar, you sound terrible, and an acoustic is quieter than an electric. xD My other reason is opinionated - I think the acoustic has a much nicer sound.
You should find out what style your twelve-year-old wants to play in, and come back to us. Base your decisions on that - is she going to simply throw in one style and switch to another? Because if she is, buying her an acoustic or a classic before giving her an electric is not only foolish, it's a waste of money - unless she wants to play in more than one style. xD Find out what she wants to do, and post again! I'm sure there're a lot of people who know lots about guitars and will be happy to give you better advice than I was able to.