Welcome on this review of many support for you to have quick access to their stuff, abilities, runes and masteries.
This Guide contains also some tips and information you shall never forget.

About me, I'm player at LoL since 2 years (s1). Nowadays, I'm playing in Go4LoL with my teams as a support and we succeed to obtain 3rd place for now. I don't like ranked since I'm a support but I managed to be Gold 3 as a jungler.

Playing support is the best idea if you want to progress in League of Legends because you will train many background skill (as warding and self positioning) and also learn general strategies.
Your role is simple, help your team by anyway available to you: help your ADC, ward the jungle, note timers, call for preventive retreat/attack... Sure, it's one of the hardest role in LoL because it's one of the most theoretical.
An advice for you, if you are a flamer/troll/leaver or whatever don't play this role because your main weapon is communication here. (In fact, stop playing LoL, it would be a relief for others players.)

This question is complex so we will do it shortly:

1. You have to ward!! If you don't know how to, refer you to a guide about this.
2. You have to write timers!!
   If you don't know them, here you go: Buffs (Blue and Red)- 5min, Drake - 6min, Nashor - 7min.
   If you haven't the eyes on the objective, you can be helped by general timers. You can set it in the More Options panel by Checking the Show Timestamps box:
3. You have to prevent ganks!! How to? Check your mini-map every 5sec and take a note about where was the jungler. Call a retreat on a lane when the probability is high that the enemy jungler is there. You also can learn the timer path of each jungler in order to expect his move (it's a long work and could be usefull only to junglers and support).
4. You have to prevent enemy' team move!! It's an extension of preventing ganks, went you will be used to the first one, you will be used to this.
5. You have to make proposition to your team!! As a support, you have plenty of free time so you have to think for the others, use ping tools in order to be clear with your intention.
6. You have to be near your ADC in order to protect him by all cost!
7. You have to be aware of the needs and weakness of your team!! This point is the hardest one. It asks you for looking at your team stuff and composition in order to tell the way your team shall play. For example, a team with Nidalee, Ezreal and Jayce shall never initiate before harassing hard. This point need a lot of experience, by now, take care of your in-game composition and watch for result. Take notes and read those again is the best way for fast improvement.

If you have choice beetween Philosopher's Stone and Sightstone (because you have the money), you have to choose the Sightstone then rush Philosopher stone uppon Ruby Sightstone, because:
Sightstone give you 2 wards every 3 minutes: means 150 gold every 3 minutes.
Philosopher's Stone stone give you 5 gold per 10sec: means 120 gold every 3 minutes.
Ruby Sightstone give you 1 wards every 3 minutes (difference with Sighstone): means 75 gold every 3 minutes

So, when you're playing support your item order shall be Sightstone> Philosopher's Stone> Ruby Sightstone
Anyway if you can't finish Sightstone but you have money for the Philosopher's Stone, finish it, don't go on a Ruby Crystal.

Since Runic Bulwark disappear, it left a great Locket of the Iron Solari. So great that even top and jungler may take it. In that case take Zeke's Herald that is now the best aura's item after Iron Solari.

But you shall have the Locket of the Iron Solari at least as the 2nd aura's item because the aura stacks with owners twice and the shield even half is great and can save an ignited team mate.

There is two way to play support in lane depending on your character:

1. You are a melee support (concern also Thresh and Nami). In that case you have to know where is the other support and aim for an initiation on the enemy ADC when time comes. It means you have to wait creeps aren't in your way and aren't a threat for your HP. You shall have every time vision on the river at least and the enemy bush in order to prevent ganks when you're aiming for initiation. Be sure your ADC and you have more HP than your enemy or the same.
2. You are a ranged support (Tresh and Nami are still concerned). In that case you must know what the other support doing in order to prepare harassment by auto attack and spells. The play style is only constant harass without putting you in danger. If the enemy is in the melee support category, be careful not be initiated when creeps hitting you and be sure the enemy bush is ward to prevent a skill shot initiation such as Rocket Grab.