Well myself being enhancement mainspec and mainly only healing heroics somewhat here are a few tips from me:
Firstly I'm guessing you will be healing heroics atm (raid advice wil be incomming most likely from those more experienced
)
You should mostly be using 4 spells and these are: Chain Heal (CH), Lesser Healing Wave (LHW), Healing Wave (HW) and Riptide (RT)
Chain Heal is very efficient if used well as it bounces to 2 targets (if at range), this is great to use for AoE damage spikes and also if you have 2 or 3 melee dps (even 1 as it will heal the tank as well)
You should try to use RT in conjuntion with LSW. LSW can be used to top up the odd group member who gets damage as it is a short cast and still heals quite well. On a good geared tank in heroics (as they arent hard at the moment) RT and LSW will be able to keep him up and these might be the only buttons you use.
HW in raids is mostly used with Natures Swiftness talent (making it instant cast) as it overheals a lot, but in heroics, with a new/not as geared tank you might be seeing yourself useing it a lot more, if he takes a lot of damage
Here are just a few tips from me, further posters can go and correct me if I have said something incorrect