1.) Always balance your healing abilities and your damage abilities because they compliment each other, making each side more effective. Think see-saw......damage a little, heal a little......damage a lot, heal a LOT.
2.) Learn to detaunt. It's a lot easier than learning to tank. You wear cloth....you are NOT a tank.
3.) NEVER run from your tank. It's very hard for them to get an enemy off you if you're running away screaming "GET IT OFF!!" I'll say it again for the slow ones......NEVER run from your tank.
4.) Buff your group. Buff yourself after you die. Buff buff buff.
5.) Heal those that ask nicely. Chances are they're taking a crapload of damage and only have time to type "heal plz" If it keeps happening, though, see #6.
6.) If another player repeatedly bugs you for heals, ignore them and let them die. If they're a ranged class they probably need to learn to stay at RANGE behind the front lines. Otherwise, they just need to learn patience.
7.) Rez the rezzers and healers first. If you have more than one person who's dead, rez the player who can help you rez and heal the group first. Chances are the group is doomed anyway, but it's worth a shot.
8.) Willpower is your friend if you're serious about healing. It makes your healing more effective, which in turn lets you do a little more damage.
9.) No matter how tempting it is, NEVER run out to the front lines of a fight. You will die.....fast. You will look like a noob for dying. You will look like a noob having to ask for a rez while your corpse is at the front of the battlefield. Stay BEHIND the meatshields (tanks).
10) prekite and dot never forget to prekite