People tend to make their job as a healer more complicated than it needs to be
Others summed up pretty much how I have played healer for 10 years or so:

* F1-8 for party target combined with mouse selecting in party window, whichever I feel like at the time. (I have had to deal with raids of 24 people - so I'm used to using both)
* Macros for special skills/combinations - not normal healing. I tried healing via macro and I just find it Bleh
* I personally don't like <mo> because I use my mouse for camera panning constantly and it leads to some awkward situations
* I don't use shortcuts for switching Hotbars - I use mouse therefore all healing based skills are on Hotbar 1
* Rearrange my HUD layout for ease of use = My Layout
Switching it around can make the world of difference
That combined with the suggestions others have offered should help you a lot