I am sure others probably have a much better way of doing the heals than I do, but on my 2 shammies I have 3 macros.

1st macro has both shammies target the party leader and cast a healing spell (can use wave, chain or whatever you want)

2nd macro has both shammies target the 2nd party member to cast a healing spell

3rd macro has them both self target themselves and cast a healing spell

I find this gives me varied options when I am taking dmg. If i only want the main(party leader) to only heal themselves I just click on the spell on the hotbar.