There are some concepts which I'm steadfast about for healers, and while it may be possible to do a good job without using these abilities, I believe there is a clear advantage to be had in making use of them.
Clique vs. Mouseover vs. Selecting targets
The first of these is click-healing. It's largely accepted that clicking your skills as opposed to using keybinds is cumbersome, but the real reason for this is that it takes you longer to perform a action because there are more phases in the process. Assuming you've always got the same target selected, you would need to move your mouse between the skills in order to press then, thus having movement lag, hand-eye co-ordination lag and execution lag. In the same way, selecting a target from the raidframes and then using a keybind to select a heal has movement lag on the raidframes(more about that later), cross-brain co-ordination lag and two sets of execution lag. Movement lag can not be avoided as a healer, however by combining the two seperate sets of executions(chosing a target and chosing a heal) into one execution(chosing a heal at the mouseover target) you've already reduced your lag by one unit. However, there are two reasons why click-healing is better than using mouseover macros:
1. Mouseover is more suseptive to "slippage"
2. Cross-brain lag
The first point means that since your mousehand is essentially "floating freely" there is a hightened risk that the wrong target is healed. This is accentuated because of the second point.
Cross-brain lag is not something you'll have heard of before. Essentially, this is to do with how your brain works, and is more prominent in men than in women. The male brain is more strongly divided into the left and right cerebral hemisphere, and the corpus callosum, the bridge between the two halves, is less optimized than for women. Furthermore the left side of your body is controlled by the right side of your brain, and the right side of your body by the left side of your brain. What I mean by cross-brain lag is when you split up your actions so that both halves of the brain is involved. This means that when you chose a target with your right hand, the signal has to be sent to your left half of the brain to chose a action from the keyboard to be performed. Theoretically, this should be slower than performing the whole action sequence with one half of your brain.
Some cross-brain lag isn't really avoidable because very few mice can bind all healing spells purely to the mouse buttons, however using a addon such as clique still helps prevent slippage and focus executive decision into one action, primarily carried out on the right side of your body.
Furthermore clique-healing has the added advantage of freeing up a secondary target(beyond the simple focus target) for monitoring such things as boss casting abilities or whatever else might be of interest.
Grid vs. Other addons vs. Blizzard
The second major issue is what set of raidframes to use. I'll start by saying Blizzard standard raidframes are horrible. They are clunky, far apart and not terribly informative and they allow minimal configuration. They aren't really an option, more of an example as to what you don't want your raidframes to be like.
Now the second option would be x-perl/pitbull/etc., these are addons which, after all, are intended for handling your frames. They allow a lot more customization in terms of size, shape and the information shown. Most importantly, they bring the frames close together meaning there is less movement lag when going from healing one person to another.
However, the hands down champion of movement lag reduction is Grid. Those miniscule boxes may take a second to get used to, but once you do the movement between any two players in the raidframe is so much faster that it promotes quicker reactiontimes. Grid also allows a very complex display of buffs, debuffs and useful information with unparalelled control. We'll have a look at setting up Grid later, as the default view is sadly quite lacking.
