I kind of dove in. I got my first horse (Norman) when I was 13 (had been taking lessons on and off for several years) and he was an uneducated 18 month old. Bad idea, I know. But my mom fell in love when she saw him on the internet and I just wanted a horse so bad that I would take the first one that came up. So we got him. It was not good, at least for the first couple years. We actually sold him once, then my mother had the bright idea to buy him back (by this time I had gotten a more suitable horse and was knowledgable enough to know it was a bad idea. She didn't listen, of course). Long story short, we sent him to a trainer and things are better now.
It wasn't that I wasn't ready for a horse. I wasn't ready for that horse. I think I would have been fine with a good 'ole trail horse. Plus I had a lot of great people at the stable who helped me out.