I have been using a dedicated healer since I hit 70 and I recently made some changes. I was running out of mana in longer fights and using way more than I needed to. Instead of spamming a heal button on my DPS button, I either just dps with my healer (on trash) or have nothing on the dps button for fights when it gets nasty. I instead bound a key near my dps key to heal. I don't have it in front of me, but it goes like this.

#showtooltip
<however you target who you will heal, I still use focus>
/cast [nomod] Lesser Healing Wave
/cast [mod:shift] Earth Shield
/cast [mod:ctrl] Healing Wave
/cast [mod:alt] Chain Lightning

I can 'SPAM' this while I fight and it has helped me conserve mana.