It's doable to carry yourself out with support. In season 2, I duo queue'd with a pretty good and consistent mid player who for the most part, won his lane. I managed to get to gold with just support. What I observed from myself and other supports is warding efficiently. Ward your lane, river, your jungle, and your enemies jungle. Try to have your adc, mid, and jungler ward as well. It helps a lot. Warding the enemy's jungle frequently, it helps so much knowing where the jungler is/is not.
As for the supports I play, I mostly played Janna, though the laning phase might be a bit rough, her ults, shield, and cc make plays that can get kills or save your team. Other supports I played were Nunu and Sona, sometimes Leona. But for the most part, I think Janna, Nunu, and Sona are the best supports to carry. And like the others said, support Zyra is really good.