Ditto what BB said about practice. I started braiding my own hair at about this same time last year and I still don't venture beyond a basic 3 strand braid. It's difficult enough to get my hair to do this without breaking it to bits, so I just leave well enough alone. Even a wonky braid is better than leaving it down when it could get into harm's way.

As far as mirrors go, I never used one facing backwards, and I can braid blind if absolutely necessary (ie. if there isn't a mirror around). For beginners, I recommend starting with a simple 3 strand braid. My best advice is to go slow, especially at first, so your fingers can get used to the rhythm of what they're supposed to be doing. After awhile, it will be come more and more comfortable and familiar. As for "perfecting" a braid, I'm afraid that I couldn't help you there. Mine still look like crud sometimes.