I usually keep a few power roots from the KoS (or whatever expansion it was...) house plant. I also have a manastone and alchemist made power potions. This and always grouping with a chanter and a bard keeps me pretty much full on any fights

However, if the fight will be long
AND heal intensive, I generally swap over to my

for the awesome proc.
But if your chanter is slacking (or MIA for some reason), power roots are the key. Get one from each tier and you get something like 10+12+15+20+25% power total, so between that and your myth clicky you get two (almost) full power replenishes.
Edit: Also don't over heal as much (also watch your wards if you don't already to wait for them to get low before recasting), and don't refresh your DoTs and debuffs until they expire. Also try and get shards/hearts if you run with a summoner :P and power feeds are nice from locks and wizzies

(as long as they are nice as well as not complete parse junkies)
And don't take offense if you already do this stuff :P I'm just stating everything (even that which you likely do already :D)