What is the best way to play a support champion?

Each support champion plays a different role (e.g Teemo would play differently than Sona, Soraka would play differently than Fiddlesticks). If you're looking at a specific support, perhaps you should ask "How do you play Sona as support effectively?".

In general, if you're claiming the role of support your biggest responsibility is do cater to the whims of the range AD you will roll with bottom lane. Often times when I play support I'll ask the range AD which he/she would prefer (Some like having the auras and diversity Sona can provide, while some like the extra control Janna can offer, and others like the extra mana from Soraka).

Regardless of the support champion you end up with there are a few important jobs you have:

• Ward: Vision is key to preventing ganks and following enemey movements, as you're support and $$ is less important to you than other roles, spend it on wards (here is a guide on it Where/How to ward
• Clairvoyence(CV): Get the ability it'll help with finding junglers, keeping up with dragon/blue/red/baron spawns, and also is useful to toss in Top's river every once in awhile(saves him from being ganked)
• Let your partner get last hits, in fact unless necessary don't even bother hitting minions unless you're pushing. If you're doing damage and your partner is trying to last hit, your damage may mess up their timing.
• Be map aware: This ties in with Ward and cv, but keep an eye on where champions are in case you need to alert your partner to back off. Also, you may get pings to cv certain locations, so pay attention.
• When possible buy an oracles elixer to help kill enemy wards. This will prevent them from being map aware!
• Do what your class is made to do. As this is class specific, I'm not going to elaborate but if your skills can benefit your lane partner use them when needed.

Playing support will take some getting used to, but they can be fun. Don't expect to be the highest level on your team, don't expect to have a full set of items quickly, don't expect to be rich. Unless your character can handle it, you shouldn't be near the front of team fights.

This is only some basic tips, and I'm sure I'm missing some, but it will get you going.

Here is a really excellent guide that covers almost all the aspects of supporting.

Intermediate/Advanced Support Guide

The guide covers:

What Makes a Good Support?

1. Awareness
2. Communication
3. Understanding Map Control
4. A Support Mentality
5. Stop Reading Guides and Play

Set Up for Success: Runes & Masteries

1. Defensive Runes
2. Tanky/Sustain Runes
3. Aggressive Runes
4. Masteries Overview
5. Effective Uses for Summoner Spells

The Usual Suspects

1. Soraka
2. Janna
3. Sona
4. Alistar
5. Taric
6. Leona
7. Nunu
8. Blitzcrank
9. Lulu
10. Less Common Supports
11. Hypothetical Supports

Items and You

1. Generally Good Ideas
2. (Highly) Situational
3. You Were Probably Going to Win Anyway
4. Don’t Get These

Who to Watch and Why

1. Nhat Nguyen
2. PureGoldenBoy
3. Xpecial

Other Resources

Excerpts from the guide:

Opportunities

Being able to recognize when it is a good time or a bad time for certain objectives is a large part of getting better at playing. If you can read the situation at a glance, it will allow you to react quickly and take advantage of these short windows of opportunity:

Dragon — If you know that both the enemy bot laners are recalling, and the enemy jungle is up near top lane, that is a perfect time for a coordinated dragon attempt between you and your AD carry, your mid lane, and jungler.

Enemy buffs — Keeping a ward at the enemy blue or red buff will let you know when it’s up. When the jungler comes by to get it is where you have a chance to steal it, gank them at their own buff, or both. Alternately, you don’t need to ward the buff, just recognize when someone is going for it and shows up moments later with that buff, like the enemy mid carry taking blue from their jungler. It’s easy to keep timers on the enemy blue in particular because of this.

Missing enemies — Did the AD carry leave her support behind? It’s like shooting fish in a barrel.

Pushing Lanes — If you’re walking all over your lane and denying the enemy AD carry farm, you actually don’t want to push their turret down. The advantage you have is yours to keep for as long as that turret is up, so use it to keep them in the lane since they feel obligated to protect it, and use the situation to deny them even more CS. Taking Their Turret Down — However, if the rest of your team is also doing very well, taking that turret will allow the laning phase to end sooner and force the enemy team into a weaker position by making them teamfight. If you want to try to sneak an early baron, applying immense pressure to bottom lane by taking the turret and then quickly backing off can do the trick.

Ganks — Keeping track of the enemy wards will let you know when and where it’s safe for your jungler to come in.

Presence

Lane presence isn’t just a huge AD carry stomping all over the enemy, it also has a lot to do with you. Here are some things you can do to maximize your team’s presence in the lane:

Contest the lane bushes. They’re the difference between being pinned against your turret and letting your AD carry have some breathing room to farm. Popping a ward into one of the lane bushes will also allow you and your AD carry to harass when they see the opportunity.

Position yourself assertively. Be present and ready to attack, and get those free hits in where you can. A support that is assertive will demand more space in the lane than a weak, passive one. Poke your head out of the bushes once in a while. Let the enemy know you’re there! If you need to go back to buy, apply some epic pressure and show yourself a few times, then immediately recall. This can force the enemy to continue to play defensively even when you’re not in the lane.

Get your jungler to gank more than once. It will scare the enemy bottom lane if the jungler keeps coming by and make them more reluctant to poke their heads out. Fight to keep your wards up. If that asshole Taric leaves to kill your ward at dragon, don’t let him get away with it! You and your AD carry should be on a support away from his own AD like white on rice.

Play aggressively and unpredictably. Even if you’re just farming and waiting for them to make the first move, don’t play too passively or they will take it as a sign of weakness. Don’t let yourself get baited by feigned passive or weak playing! Heal baits are easy to fall prey to.

Summoner Spells

Coordinating with your AD carry is the #1 advice anyone can give you. It is highly advised that they are the ones that take Heal and not you, as they need to stay alive moreso that the Support does — every second the AD carry is out of the lane they are missing experience and farm. Heal can be their panic button.

Secondly, taking Exhaust as the Support allows you to use it in tandem with your initiations on an out of position AD carry. Controlling when the enemy AD carry gets exhausted takes some of the strategic weight off your AD carry, and allows them to simply rely on hitting the “oh shit oh shit” button for their summoner heal.

Flash is really up to you, some supports almost have to have it to be effective (Alistar), other supports don’t really need to bother (Soraka). If your playing style requires you take Flash, go for it. The mobility of Flash as an escape is more necessary on melee supports for mechanic reasons alone, so just keep that in mind.

Ignite can also be useful, great against Soraka heals and for double Heal lanes, not to be used for picking up kills unless absolutely necessary. This is pretty iffy; again, coordinate with your AD carry. Your communication with them needs to be rock solid if you’re going to skip Flash and pick up another aggressive summoner.

Beyond that, unless you are playing a roaming sort of support which isn’t really covered here, you don’t really need anything else for Summoners. Why not Clairvoyance? Well… Unless you’re playing at tournament level, competent warding by your whole team will do the job. It’s also a twofold effect in the mindgames of bottom lane: when you see a support with CV instead of Heal, you know they’re missing a more offensive summoner spell like Exhaust, and it’s that sign of weakness which makes it that much easier to walk all over them and take control of the lane.

Clairvoyance shines late game when you need critical vision in one area, but the cooldown is frustratingly high and again is taking the place of another summoner that might afford better utility.

Early game: You want to be in the lane with your carry, and let them farm. Keep them alive, protect them and don't steal their farming. Help them harass but let them take the kills. You should be putting your skillpoints into the spells that bes aid your carry. For example, as Janna I always max the shield first for the protection and the AD bonus. You should be warding consitently during this begginging lane phase.

Mid game: You should still be warding and supporting your team, never wander alone and always keep your teammates safety in mind. Keep an eye on the map and call MIAs and start building some of your base items. You want to build survivability that will benefit not just you but your team. Aeigis, Frozen Heart and other aura items are great support items. Always be using your CV(which you should have) to scout the enemy positions. Keep an eye on your carry and go with them to perform ganks.

Late game: You should be focusing on being there for your team as a whole, whatever they need in those teamfights you deliver. If you find your carry is getting focused then make sure to use your interupts and shields to keep them alive, if the carry is ok then defend and heal the tank if he is taking a lot of damage. build your build around what you are needed for, sometimes if your team is very sustainable you can even afford to beef up some of your damage! (not likely). Continue to ward river, Baron, their jungle. Late game CV will make or break the game. Learn how to use your skills to get an advantage in those teamfights, support characters can be very disruptive and effective.

Random tips: Gold generating items such as heart of gold and philosophers stone are great on support characters. You will be surviving on assists and have to buy a lot of wards. It wouldn't hurt to put some points into the gold generating mastery. Remember when building to keep your team in mind. Don't just build AP and think that will make your heals more effiecient thus making you a good carry. You also want to have good unique items with good auras.

Basically a support player needs to forsee tragedy before it happens. A well placed Wish from Soraka can make or break a teamfight as can a well place monsoon?(jannas ult). By giving your carry or tank that extra sustainability with that kill they thought they scored could break the whole team. A monsoon can save teammates or place the enemy carry in a bad place.