I was doing well in ranked and got up to 1374 elo. But I lost one game and it was downhill from that. I lost 8 games in a row (6 of them I had a more than positive kd ratio). I try to keep my team's hopes up by staying positive in chat and I myself am always positive and never rage, but having an afk'er makes my entire team rage and even before that game everyone on my team (5v5) was raging at everyone including me, even though... I was doing well and in fact doing the best on the team. I read and follow every tip I see about ranked but it just isn't working for me for some reason. Any thoughts?
In my opinion, 15 games is too small of a sample size to say that your methods just don't work. While taking a step back after each game to figure out what you could have done better is a great idea, I would suggest that you just keep playing until you've got enough games under your belt to reach your more-or-less "true elo". I draw this conclusion from baseball statistics and player psychology -- for example a batter might be mired in a 2 for 20 slump, but that doesn't mean he's necessarily doing anything wrong; he could just be unlucky (like if he's hitting the ball hard, but just right at the opposing team's fielders.) Such batters are generally discouraged from making severe adjustments to their approach at the plate unless there is clearly something wrong with what they're doing.
From your own description of your play, it sounds like you're doing the most important things right (positive K/D, being a team player), so I think it would be hasty to assume that your play requires a drastic change.
Although I don't know at what point Elo "stabilizes" and you reach your true Elo, I think that 100 games played would be a fair number to go for. At that point you'll have gone through numerous win and loss streaks and be able to draw a more data-driven conclusion about your own ability.
For more reading about sample sizes and when numbers stabilize, check out this article. Although baseball stats may be the subject of the article, I believe that similar conclusions can be drawn for any sport that tracks statistics, including LoL.