I don't think I've ever written about the way that I do my two-strand twist. It's not a big thing, but I know it has helped me a lot when it comes to helping my twist stay in longer.
I always braid the first inch and a half of my hair and twist the rest of it. I find that doing this prevents the roots from getting frizzy to quickly and prevents it from unraveling at the roots by the 3rd day or something.