Climbing in Low ELO is all about consistency.

Its really about whether or not your teammates feed too hard for there to be a realistic chance of carrying them.

Not really I only play MArksmen and I'm climbing steadily.

Nah, it's all about knowing how to carry teammates. That'll win you games more often. Else you'll do well, but unless your teammates are also doing well, you won't be able to carry and win.

To win at LoL you have to accept the following ancient truth:

You will have roughly 40%-45% losses and 40%-45% wins.

You will have 10%-20% games that are really even and close.

It is all about being able to win these 10%-20% of games in order to climb, because it puts you at more wins than losses.

That is the one and only secret. Be the deciding factor in these even games. Even the cremé de la cremé of LoL players will have games they can't win. Watch the VODs of the World's players when they SoloQ - they definitely do not win every single game!

Or you know, one-trick one of the obviously broken and OP Champions that can 1v9, lol. But if you don't want to be that guy, focus on what I wrote above.