I don't really combo my vigors, I don't like to use a lot of salts at once. Right now I've tried almost all guns and vigors and I've got a pretty sweet setup right now.
I've got gear that gives me +50% speed when shield is down, and I get HP any time I meelee kill anyone.
With the Carbine and Charge, I can pick off guys with headshots as I enter combat, then when my shield goes down I sprint with my bonus speed from my gear then when in range I use biotic charge to get full shield, and proceed to meelee those around me to regain all lost health.
If necessary I finish the rest with bucking bronco and burstgun, if any are left.
