What on earth......The main way is to simply PvP, especially in rated PvP. Your personal preformance doesn't matter TOO much in the overall flow of rated BGs (Even if your actual skill is average, as long as you have a steady group capable of cooperating, you'll do fine).
A better way is to find a buddy who doesn't do much of anything besides questing/soloing, and invite him along while hes doing his own thing. Que for rated 2s. Buddy stays out, you go in. The higher you can climb, the better you are (Tack +500 onto whatever your eventual rating is. If you settle down around 1100, then you'll likely not be able to go too much above 1600. If you settle around 1600, then you can probably climb up above 2100)