Pretty much what Tolmos said.

You can keybind your pet hotbars and use them to your heart's content. What I do with my Eos is, I put her on "Steady", place her near the tank (this way she'll always heal anyone nearby at ~80% HP), and monitor her abilities CD. I'm personally fond of Rouse+Fey Illumination+Whispering Dawn combo as it gives massive heals. "Steady" will make her only spam Embrace. Do remember to put her back to "Steady" after you activate her abilities though; don't want her to automatically use them again.

If your fairy is following you, she might not heal (or in this case, "register" to heal) fast enough, so use your keybound Embrace manually. What's cool about this is, you can spam it while you move around avoiding AoEs and other craps (helped me heaps in Titan HM). If she dies, you can quickly Swiftcast+Summon again.