You're an ADC main?
Also I would recommend playing only support champs that are hard to mess up on, i.e. Leona, Soraka (She is OP atm, but underrated), Janna, Sona, Tahm, etc. Blitz only if you can land hooks on carries, not tanks.
A good example on who not to play would be Thresh, he can carry really hard, yes. But you have to land amazing hooks and know how to flay good consistently, 99% of the time. Also being tanky on him helps you teams tons, but no one seems to get that tanky on him till late game. I see so many support thresh's in silver and it honestly infuriates me as almost all of them are terrible. If you're looking to practice with him in ranked, go ahead, but don't expect to gain elo with him.