I'm a new healer too, and the advice here is really sound!
The only advice I have as a fellow newbie - practice, practice, practice. If you have a friend in the game and can practice healing him/her on some heroics or even mucking around questing, do it. Find a keybind scenario that works for you - whether it's clicking, function keys, keys on the mouse - whatever seems easiest and most instinctual is right for you. Just go with it.