Okay, well here's the deal. If you get too comfortable with one position, in my opinion, you get too comfortable. It's like the car crash within 10 miles of home thing. You get too comfortable, and you lose. In my opinion, let the bads troll about, take their roles, and you pick up the scraps. I always fill, because after a while of calling mid all the time, I'll admit, I start to slack. I do good 3 games, then I feed one, because my playing isn't at its peak anymore.
Basically what I can give you, is take 3 champs for each role, familiarize yourself with them, and just play them. Make sure they all are good at different things. Like I wouldn't pick Syndra, Annie, and Veigar, because they are all 3 single target burst champs (annie less so, but still). They all fit the exact same role. What I would do is categorize them in to subroles
Top Laner: Bruiser, Ranged, Magic - This allows for counterpicking with your 3 selected champs, with a variety. Use a similar format for all of your lanes, and you'll be pretty well of. For me, that list would be Elise, Cho'Gath, and Nidalee. These 3 fulfill very specific roles, Cho'gath being a magic tank with Hard CC, Elise, being a Bruiser Magic Assassin with a hybrid of range/melee, and Nidalee, being similar to Elise, but of a more sustainable format for lanes against people like Cho'gath and Yorick, where sustain is necessary.
Though I would never exclude yourself from branching out. I wouldn't suggest playing a champ for your first time in ranked, but always feel free to pick a champ you feel would be effective in a given situation. I don't play Trundle often, he's like my 4th string jungler, but if I see a Shyvana jungling, I grab him, whether I'm top lane, or jungle, because he's a very effective counter who can SAFELY be picked and manage himself in a lane if needed.
The number one key, is to always be having fun. If you get frustrated. Stop. Take a break. Play a normal, or ARAM. Get back in to the swing of the fun of the game, and you'll play at peak performances.
I know people can be frustrating, they can complain, they can make mistakes, the best attitude for that is "**** happens, just make sure you do better next time." Don't get down on yourself or others for ****ing up. It crushes morale and really just ruins their performance. Constructive Criticism, or a witty joke can ease the pain of loss.
The primary goal in ranked is objective control. The goal of the game is not to have the best scores or the most damage done. Gold is what makes you win games. One player's death for a dragon kill is one hundred percent worth it. Kill the carries before the supporting roles, and they'll be worth more gold. Maintain presence in your jungle, and kill the little guys (wraiths/wolves) when you can afford to.
Laning is an essential part of the game. Practice last hitting and get as good as you can at it. It's the most effective way to gain gold without placing yourself in danger by pushing the lane. Harassing is important, but not if it means missing a minion. Note that minions are worth 25~ gold a piece, and a kill of standard value is about 300. That's about 13 minions, and you've effectively killed a champion.
Always watch your minimap. If you're not already used to paying VERY close attention to what your teammates are doing, now is the time to start. Your allies can't always be there to hold your hand, so be open-minded, keep your eyes peeled, and you'll probably open up to some interesting opportunities in which to take advantage of the enemy team (5bot, push top, 5 top, get drag/push bot, etc etc.)
No champion is bad. All things are viable. The only question is: Which ones are better than the others. I know you've experienced a lot with Zurri, and I know you know his ideas are outlandish, but just look at what the meta is today. His ideas were far before his time, and you know it.
@The guy above, your progression matches definitely don't reset you to 0. Only 75. Nice try, though. O.o
I strongly recommend looking at guides for characters you already know. They can have neat little tid bits that are at the very least interesting to read, and possibly even more so helpful with something you may have overlooked. They are not bibles, merely ideas on paper.
Make friends. Find a good player? Throw him an honor, friend him, ask to play again. Duo's can be good. They can also be a terror. There's nothing worse than the "We duo bot" combo that always ends up feeding. Make sure it's someone you wouldn't think twice about. Synergy plays an important role as well. Passive players don't roll well with aggressive players, etc.
Make yourself known to the higher win-rate champions. Which ones to ban, which ones to pick and trade off if people want them, etc.
At this point, don't be afraid of dodging. I wouldn't do it in excess, because you lose a rather miniscule amount of points, but for sure keep the option in mind. Feel free to troll pick and try and get someone else to dodge, then dodge at the last possible second (Never dodge before the 2 second mark at the very least). The point loss is nearly 1/4 or 1/5 of an actual game, but still, better than getting in, and losing horribly. Unless you're at least 51% confident your team won't go 0/5 in the first 2 minutes, I'd feel free to dodge. xD
Some important Resource References I would strongly suggest using would be:
^Those resources really come in handy. Use them to gauge who goes what role in your teams, what champion to counterpick as, statistics about champions. Popularities, winrates, and all that. Patch Notes, articles about theorycrafting, numbers and stuff. I'd also strongly recommend you LoLking suspicious characters on your team, so that you may judge whether or not they are any good. xD
TL;DR. Play the game for fun, in a competetive manner. Don't be a troll, don't be jerk, don't be that guy that says "mid or afk." Play the champions you want if they suit what you need, do not play champions you don't know. I would never take Tryndamere in to a ranked(Personally). Ever. Grab a friend you know is good that you synergize well with.