I second your request for advice. If anyone is good with these, please submit some.
I haven't gotten the hang of these either. I have the regen on hit perk as well, but they still drain my mana crazy fast and don't seem to gain me much mana on spell hits. It breaks a lot too, even with mildly weak spray spells being used on a Steadfast or even Greater Ward.
I read one tip that said they take a few seconds to get to full power, but haven't tested that much since learning it. Feels like the couple seconds used to charge it up would waste too much mana, but maybe I need to upgrade magicka more.
All in all, just healing spell damage has proven more mana efficient so far, but I'd like to learn to use these for combating powerful mages as they hit me pretty hard when they spam certain spells.