Advice for playing support (read: ward bitch):
1) To start, buy 2 wards (1 if someone else can afford to). Give one to whoever's going top Legion/bot Hellborne so they can counterward the pull (assuming you don't have some other method of counterwarding)
2) Other items depend on your hero. You want at least 90g worth of regen. Get Mana Battery if you think your lane is going to be super spammy, get Guardian Ring and build it into a Ring of Sorcery if your lanemate has mana problems. Get one/two minor totems with what you have left, or you can opt for another potion.
3) If your lane mate is taking heavy damage, give your regen to him. It's more important that he stays in the lane.
4) Focus on denying and harassing.
5) Pull, if you can, but only if your lanemate can safely farm without your presence. If they are getting heavily pressured, then skip the pulling and stay and try to alleviate some of it so they can get in hits.
6) Try to get flying courier before your mid needs to buy bottle. It can be a bit difficult because you will be surrendering your last hits to your lanemate whenever possible, but if you get an early gank, or if you're getting farm only because your lane mate can't risk himself, then upgrade.
7) Ward either rune before 2 minutes so mid can grab the first one if they need to. If they are up against a blinker, feel free to camp the rune in order to steal it from the opposing mid.
8) I don't have a list of ward spots but there are a few obvious positions. There are the cliffs on HB side overlooking top rune, the cliffs on Legion side overlooking bottom rune. There's the high cliff near HB's base, at top, and the high cliff near Legion's base, at bot. Other locations will depend on the teams' strategies/overall situation of the game. If you're not sure where to ward, ask, or give the wards to someone else.
9) When you play a hero like Dsham or Nymph, there are two options for skill builds. You can level heavy babysitter, heals, restores, shields, that stuff. You can also level support/ganker. Your choice will depend on whoever you're babysitting, adapt your build to suit their needs. Again, ask if you're unsure.
10) If your lanemate can handle the lane by himself, and your mid is having trouble, try to get a gank in on mid (assuming you have the appropriate skills) rather than staying in the lane when you're not absolutely needed.
11) If you know that mid is an exceptionally good player, and that the people in your lane aren't, you should be on the look out for potential ganks, especially when scouting out runes for your mid.
I don't know how to play counterwarding mind games so someone else will have to answer any questions about that.