The first rule I have when healing is what I like to call, "The First Term of Engagement." This is my firmly held belief that the melee-DPS type should hold off, if even for just a few precious moments, before entering into a full-scale brawl. We all know that your overall damage is massive, but there's no need to be the first corpse on the field. Running face-first into oncoming traffic can (and more often than not, will) produce that result, so why do the same with a blob of red names? Leave that job to the (far) better-prepared and better-geared tank. I can't count the number of times I've watched squishy melee-DPS be the first to redline on my Squared addon. The sad thing is, it still surprises me. Every time. And all I ever hear myself say is, "Why?" And this goes for you two-hander-wielding, Focused Offense
-running "tanks" as well (i.e., if you're running the FO tactic, you're not a tank, you're a squishy -- so act like one).
Simply put, being the first to die is effective at a few things, and neither of them is good. First, your healer is no longer healing, but is casting a resurrection spell instead. The domino effect starts to happen, as others are dying from lack of heals and are in turn receiving resurrections instead of heals, so on, and so forth. Second, like in American football, the home-team has "lost a yard," and the lines are inevitably pressed back. In this case, even a well-positioned healer runs the risk of being exposed (and to follow the analogy, of being sacked). Furthermore, those waiting for resurrections might never receive them on account of being swallowed by the push.
The first rule also goes hand in hand with target selection. Don't be afraid to take the time to be picky -- although that juicy swordmaster has lots of hit-points to subtract, that white lion your tank is bashing on is probably worth his weight in renown. This aspect of the "First Term" is really just common sense. Pick your targets sensibly and aggressively. Be selective.
Ideally, if you've followed "The First Term of Engagement," you're in the mix and knocking things down with head-rushing authority, all the while hidden by the flailing of the various instruments of death all around you. But things can (and will) go wrong: You might take a wild axe swing or two and find yourself in need of medical attention with none seeming to come your way. This is when "The Five Second Rule" comes into play.
It is at this crucial point during the battle that you should disengage (if you can), take your tunnel-vision goggles off, and have a look around. Every swimmer or diver needs to eventually come up for breath, and so should you. Analyze the battlefield. There is probably a good reason you're not being healed. Is the tank running low? Has a nearby friendly died? Is your healer in trouble and in need of desperate and immediate assistance? During the next five seconds, you should ask yourself all of these questions, and then do something even more important: answer them. If your tank is running low, remove your Guard
buff (if you have one) and give him a little breathing room with his health bar. If someone else has died, you might want to consider repositioning; either cover-up your fallen comrade or be prepared to fall back against an advancing enemy front-line. If your healer is getting his/her quarter-hourly spinal tap from a witch elf, you might consider buffing your killing blows with this de-stealthed and otherwise-preoccupied freebie.
Basically, the second rule deals with general awareness. It is easy to get lost in the madness with the blinders on, so take them off and lift your head once in a while. If you can help to find and address the problem (the problem of you not being healed, and why), you'll be doing your whole team a favor, as well as giving your healer the crucial reprieve he or she might need to recover and resume healing you. Shouting in chat and calling out "bad" healers is not an example of following this rule.
In general, if you follow the first two rules where you hadn't followed them before, you should notice a marked improvement in not only your own performance, but the performance of your team as well. My third rule doesn't apply to any particular situation, but rather to all situations at once. I call it "The Law of Accountability." If you've heard the phrase "survival of the fittest" then you know what this rule encompasses. Essentially, you should be responsible and prepared for your own survival -- a good team is made great by members who know how to prepare and survive. Don't be afraid to pack a few healing potions. Running away should never be considered an act of cowardice, but rather an act of self-preservation. Take your virtual-gaming death seriously. The more ways you can help your team, the greater the profits will be in terms of how much fun you have. You'll earn the respect of your peers and the ire of your enemies.
In conclusion, I'll attempt to summarize my rules as briefly as I can:
1) Don't be the first in. Hide and Seek (and Destroy).
2) Don't be the last out. Disengage and Analyze.
3) Be accountable. Prepare and React.
Oh, and finally, always remember to have fun. It is just a game, after all.