Carry your team! Watch the whole map, warn them when to backup, when to ward, etc. Tell them when to teamfight. When to get drag, etc. Kinda got to win it on your own. But tbh I'm lower ELO than you at the moment from duo'ing with a very low friend lol, so maybe I'm wrong. But I've been moving up slowly, however, so I guess I'm doing something right. I do it by jungling. I can often win a game for my team through jungling, especially with controlling champs like Nautilus and Nocturne, etc. Just keep playing, you'll start winning eventually. You may be losing ELO, but you'll gain it back just as fast if your in the right ELO.