I'd like to improve my gameplay, make some friends, and rule the world... I mean... Join a team.

I'm kinda tired of being stuck in bronze, I've improved my game but I get frustrated by bad teams or cocky in my abilities and I always jump in and get killed in a team fight. That's my number one problem, I know this is a problem, and I'm working on that problem. However there are many more issues I'm having that seem to separate me (bronze) and youtubers/twitch streamers (gold/diamond and up) that I've noticed and I'd like to learn how to get better at the game.

My issues seem to be strafing, last hitting, knowing what to build other than defense (I've started looking at my opponents items and stacking defense against what seems to be killing me the most), poking the enemy with basic attacks (I'm decent at getting the occasional skill shot in), and positioning.

I was rusty, as a matter of fact I just started playing again after about a year hiatus and the few people I played with are no longer on and the ones that are on are pretty much out of my league and unwilling to help. I'd like a tutor, or preferably a group of tutors willing to help me improve my game. I'm a fast learner, it's just that I took the break and now for the 2015 season I'd like to get up to at least gold if not higher in ranked. I play just about every night (est) after I put the kids to bed, I'm a mature gamer and I try my best to be a team player.

My mains are mid or adc (I'm trying to get good with but of course I'm not there yet) tank (Jungle or top, but only if we need the tank) or support (I've turned them into carries if the game lasts long enough) Top (if we have a good figher/tank jungle) Jungle if top is tank

TL;DR I'd like help with the list in the second paragraph if any tips are available I'd also like to find a tudor/group to play with, so I listed my mains at the bottom.