It seems to be the hardest position to play. If you're in the top lane you can carry the game after killing your opponent. If you're in the jungle you can kill the entire enemy team because you control the map. If you're mid you can push down the shortest lane and carry other lanes. If you're adc you do the most damage in the game.
But support relies on your team doing all the work while you shield or heal them after an engage.
What are you meant to do?
Lost R2 votesYou have to be the hardest, most brutal and pragmatic motherfucker in the game, because you are going to be the only fucking person who will ever notice the weaknesses of your team and the strengths and weaknesses of the enemy team. More often than not, you will be the only thing that balances out your entire team of AD melee burst assassins.
And expect people to only hate you for it. Expect them to four-man report you. Expect them to SWAT you. It is the most thankless role in the entire game, so unimaginably mistreated and stigmatized that people would rather get permabanned than be a support for a single second. Don't expect anyone to ever listen to you, either.
If you aren't ready for any of this, you are not ready to be a support.
Tahminatrix 1 votesPick something that benefits the current snowball meta, 
can regularly help prevent your teammates from giving shutdown gold. (Atleast until they gut him soon)
One of my favorite tactics as tahm is to keep my eyes on whoever is carrying the enemy team, if a group fight breaks out I can try to keep them isolated / stop them from doing anything until its too late. (Good thing this requires a lot of vision control so you get to feel good about using wards despite half of your teammates not even knowing they have a minimap)
is reliable at stopping enemies from escaping by using polymorph so they cant dash or anything. (Zed loves beating up cuddly creatures)
is a good kamikaze champ that can get the enemy team low enough to take inhib turrets.
Baron Barian1 votesThere are a bunch of small things that a support needs to do that all add up to one big thing. It can be hard to carry as a support though since you're not suppose to bring the damage, which is easy to notice in game, where only the flashiest of all of the supports ae consistently noticed at all points of the game.
At the end of the day though, a support's job is to help their team. It starts by making sure their ADC stays alive, farms well, and even get some kills in, and then it evolves later on into helping your entire team. You usually build the right items in your games as Sona since they synergize well with her healing and provides much needed utility and extra healing for your team.
One big thing that too many support players neglect though: Warding. Make it a habit to place new wards down in areas where vision is needed, even if you already have 3, because you may want to put new ones in more desirable spots. It's why you should always fully upgreat your support item and why you should always carry at least one control ward.
Cocho1 votesShield/heal supports are often just crazy lane bullies ironically. Janna, soraka, or lulu can poke out and out trade a lot ADCs early. You also have 3 pots to their 1. Just harass them early and take good trades.
When you're winning bot you can,
look for times to roam mid, ward the enemy jungle to help out yours once you take bot tower, you could go top with your ADC. Or mid.
alot of ways to impact the game. Or you could just pick a support that isnt heal/shield.
PopcornBunni1 votesShield/heal supports are often just crazy lane bullies ironically. Janna, soraka, or lulu can poke out and out trade a lot ADCs early. You also have 3 pots to their 1. Just harass them early and take good trades.
When you're winning bot you can,
look for times to roam mid, ward the enemy jungle to help out yours once you take bot tower, you could go top with your ADC. Or mid.
alot of ways to impact the game. Or you could just pick a support that isnt heal/shield.
How do you take good trades? It feels like every adc has more poke range than me and removes half my health in two auto attacks,
Cocho1 votesLets say you're janna, and you W, auto, shield their auto/ability, then back off. Thats usually pretty good if you only take one auto attack and dodge their skillshots.
It's better to go for trades when they use something or the wave, or when the ADC wants to last hit a minion. He has to choose between last hitting the minion or hitting you. Also works when they're doing this to your ADC. If they want to hit your ADC, you have to position so they'll take damage from you for doing so. (and vice-versa if your ADC is good)
Also it depends on whether or not both of the enemies are in range to hit you. You dont want to take too much damage and you dont want to give them much time to trade back. So using everything at max range is pretty important. Also easier to dodge things if you're at your max range. Idk if you're familiar with the term spacing from fighting games, but thats basically it.