Well, support can make huge difference in games. In lower elos, I mained Soraka (no one would be smart enough to focus me most of the time). My secondary main was Janna (although it is my primary main now, since Soraka is too risky in higher elos due to full engage comps and my lack of mobility). Soraka can do a lot of damage and be wicked good at zoning. And sustain in lane, of course. This meant we were guaranteed to win bot. When I hit 6, I can help other lanes win fights due to my map awareness and ult. Increasing our team advantage even more so. I always love saying how Soraka counters idiots on my team, who are usually people that are too agressive for their own good. I once won a game in lower elos where our Yas was 1/11 at one point having fed the fizz mid. We won because I eventually just followed him and healed enough that he could win any trade.
As Janna, in higher elos. I actually do a decent amount of damage if people leave me alone and let me. Believe me, I have 1v1ed ADCs before who have tried to auto towers with me next to them, thinking I would do no damage. Give me like 4 or 5 seconds and I take like 3/4 your hp pre-lvl 8. Also, I am able to roam easier and get a lot of kills for mid (especially if the jungler comes too). Janna, similar to Soraka in lower elos, is a champ that helps to idiot proof my team.
Overall, the most important thing that helps supports is map awareness. Supports provide the biggest impact by providing information to their team, whether it is through wards or through MIA awareness. That and making sure their team lives and suceeds in fights. Supports enhance a team's skill level. Good teams can win with a bad support. But a bad team can win with a good support. Also, sticking with the same couple champs for support up until plat will make you climb faster, since your mechanics become second nature and now you can spend most of your focus on map awareness. Strategy, map awareness, mechanics, A GOOD AND NICE ATTITUDE, and general information (like cds, where people are, etc). That is how I climbed so fast.
Also, thank you. :3