Lol playing support really isn't an easy way to move up the ladder. Having a support that actually knows how to support well against a team that doesn't have a good support (aka somebody who goes Swain or Tristana support because they're forced into that role) improves your chances of winning, but having a toplaner or a jungler or an adc or mid that knows their role against somebody who doesn't know the role well will also improve your chances of filling.
If you're good at all the roles, making sure that everyone gets a role they're good at can help improve your chances of winning. I'm sure you've had those games where last pick is quite until it gets to him and at that point all you need is a jungler and he's like 'I can't jungle'.
How to carry as a
- Toplaner-find a bruiser that can splitpush well and take teleport. Push top towers like crazy and force the enemy tem to come stop you every 2 minutes while the rest of your team is applying pressure in another lane. Have teleport for those scary botlane/midlane ganks, to get back to splitpushing faster, to join a teamfight that started without you. As a toplaner if you can farm up, become tanky, and play someone who mows down towers you can pretty much singlehandedly win the game as long as your team doesn't feed to the point that the enemy team can 1v1 you and as long as your team keeps pressure along the map so that it's not as easy to send a whole team after you
- Midlaner-play somebody who scales well late game, snowballs, and roams well. Assassins can single handedly win a teamfight if they're good (in play+ ranked games Akali currently has the highest winrate in both top and midlane this patch), in lane if they're good roamers they can crush the enemy top/botlaners to keep them from getting fed and help spoon feed other lanes kills/assists.
- ADC-play somebody who scales well late game and farm it up in lane. If the enemy team has a decent amount of dashes make sure your ADC has some sort of escape, dash, peel. Your job is to attack whatever you can safely. You want to be the last one standing at the end of the teamfight so you can push the towers. If you're playing someone who hypercarries late game and you're good at them, you can pretty much demolish the whole enemy team with good positioning and allies who understand you're currently 15/2 so they should peel the enemy Maokai off of you.
- Support-I'm a firm believer (as a support main) that this is the 'fill' role. If your toplane goes teemo, go Braum or Leona aka someone tanky. If your midlaner is Zed go someone with good AP like Karma. The easiest way to carry playing a support champion though, is good warding (if you ward well and have a good adc you can easily turn an enemy jungler gank into a triple kill for your team) and then either carrying your team by being this cray tanky cc monster that they can't get past, or by being this bursty as hell mage who one shots you with her ult (or a Zilean bomb don't forget the OP troll bomb of feath). Or Soraka/Janna, Soraka is always good for that dumbass up toplane thinking he can still 1v1 the pantheon who not only counters him but is now 3 levels ahead. The ult is also good at turning ganks in top/midlane into a double kill (and a double assist for you) if you're watching the map right. Janna is just the queen of peel. Teammate tries to 1v4, walk in, tornado the enemy team, pop your talisman and say 'bye bye' to the enemy team getting that free kill.
- Jungler-dragon control and good ganks. Dragon is so important this season, play someone you know you can get in and control dragon with but not just dragon make sure it's somebody who ganks well, and you can gank well with. Why? because getting kills/assists from ganking means that when you go to a lane that's behind to help them out, you have the levels/damage/tankiness to win that exchange too. If you're having trouble getting started find a lane that looks like it's winning and gank it for an easy assist/kill. If botlane is losing lane and you're 0/1/0 don't gank it unless you're sure you can do something there, your 3/0 midlaner for the xp/gold and then go bot when you think you have an advantage over the enemy botlaner. Also counter jungling/ganking. If you can make the enemy jungler obsolete, it's pretty much a 4v5. Your welcome team, their jungler is 0/5 with approximately no cs
I'm sure there are other things involved too, I main support, but really carrying the game is about A) winning your lane instead of bitching about other lanes doing bad B) winning your lane so hard that it effectively becomes a 4v5 in terms of who is useful, and then C) push the objectives around you so that the whole team has to come stop you while the other two lanes get free objectives for your team. Pretty much if you get ahead, buy some wards and ward along where you're pushing and just start taking all the towers. If you have good enough vision the enemy team will waste their time coming to stop you and you won't be there.