Ok the most important thing for climbing in ranked is pick to roles (particular ones you can easily carry, mid and top are best then jg. But in low elo jg can be hard because team doesn't understand your purpose. You can go adc, but it is much much harder and don't bother playing sup unless u want to be carried). Ok after picking your main roles learn anywhere from 2-3 champs per roles the fewer champs the better you will get. For mid in low elo I would only play Annie (super strong, high burst, great control of game, even if counter picked people in low elo such as bronze don't understand her power. For top darius, garen and mal are all simple and good in there own ways. mal has beast ult which can win games, dairus and garen are strong in lane and strong tanks with little counter play in low elo. The idea is we are not Pro players we don't need to master every champ. Also use op.champion.com for builds and such.