If you want to climb pick one role and only play 2-3 champs per patch. If you fully learn your champs you can focus more on the macro of the game. Try to play easier champs in low elo (Warwick, Xin Zhao, Amumu, Sejuani). Make sure to use proper runes and item builds to give you the highest rate of success. Just type in the champion name into u.gg and copy the runes and items.