Solo healing HM is so much fun, I like to do laps around the arena to also keep myself pumped up! Also be sure to stay in middle during line bombs to tempt fate, and race the circle bombs to see if you can outrun them before they catch you!
Also don't forget to stand where the tank is standing during X bombs, and time it right so you don't get cleaved, because if you do you lose! You also have to play WOTLT, Weight of the Land tag, run to your friends and see if you can get them hit with WOTL, if you do, they have to do the same to you!