Iv wrote some mini-guides on the forums, therye out of date, but much of the information is still relevant, and some people liked them.
Support
http://boards.na.leagueoflegends.com/en/c/GD/orEfTYAJ-tips-for-support-position-inside
This one I still had the link for, but less about position tips but a teamwork guide to help ur jg gank
http://boards.na.leagueoflegends.com/en/c/GD/eEu3WpN2-making-your-lane-gankable-a-mini-guide-for-people-who-want-ganks
The easiest position in the game is Top (getting atleast 100 downvotes from deluded kiddies who think its super hard).
Here me out, its a solo-lane for ur team usually, and usually for the enemy team. This means only one opponent to have to concentrate on. There is only 2 real ways for the enemy jungler to gank from, and one of them is from behind your turret. Its very easy to ward against ganks in top lane.
If youve played a fair bit of ADC, transitioning to suppport shouldnt be so hard. Youre used to the duo lane, you just need to learn some sweet warding spots. How to peel, and how to poke, all while keeping your eye on the minimap more than anyone else on your team.
Mid is the most gankable lane with up to 7 angles to gank from (7th being from behind your own turret). Fortunatly the gank ease is offset by the lane being very short, meaning you dont have to run far to get under your tower. Mid also being a solo lane has little in common with top. In mid lane the champs are often 1v1 specilist that are very good about going in on a mistake, and if they can, will add YOU to their farm.
Whatever you try next, just buy items for sustain, and make good use of your pink wards and trinkets. Remember pinks now cost as much as the old stealth wards, and we get more money... BUY ONE! Play it safe, you will see many other kinds of champs in the other lanes.
If you only really play one position, youre not ready for ranked. Its foolish to think that everyone is going to step aside for you to be ADC every time.
I hate to say this to you, but that whole "The only role I play is ADC" tells me you CANT be good in a ranked game. You dont have the experience those other players do. You have that one thing you do, ADC... great, everyone else there knows how your champ works, and how theirs works, and every other champ on your team. Down to cooldowns, ranges, burst potential. You have that ONE thing you play and have to guess without first hand knowledge what they can do.
There are 5 META roles in the game, and you only know how to play one. Youre in no way ready to play a ranked match if winning to climb ranks is your goal.
I suggest you start doing a bit of guide reading, then trying out what you read. When it comes to your next match, call "fill" and take the role no one wants, or call jg, or anything. DO NOT QUE UP FOR RANKED till youve educated yourself.
I dont want to sound like Im trying to be hard on you, but most of the people who claim to main ADC are self absorbed asshat kids. More so for those that claim to play ONLY ADC. You dont want to be that person. You want to be the player that can do anything.
Read some of the WIKI, watch some champion spotlights, look at some youtube vids.
ADC mains if they can find a champ that they like, tend to transition well to TOP lane. Once youve learned to solo lane, try some mid. Save Support and Jungle for last, your team depends on you in those roles, and honestly a person who only plays one position goes into ranked without knowing how to play all 5 roles isnt big on teamwork I dont think... Save those for last, and look up more guides and videos to help you, then try to play with a midset of "Help my team" instead of "IMA CARRY THIS BITCH WOOO!"
Good luck.