I'm nearly Diamond. Now, what?

I originally made a post questioning how to improve past points that others see as a milestone. I received a lot of good feedback about how to improve, and I hope to get some more.

I'm nearly Diamond, and I got here mostly by playing my own weird picks and using my own ideas on how I think I could win the game. I supplemented this with listening to others' ideas and comparing them to my own. Now that I'm hitting another wall, I have more ideas for improvement. I think I should join a community and write guides to get appropriate criticism on my ideas and listen to others, since a majority of my exposure to League is through the boards. What communities are out there?