Couple things I've picked up on:
Use your power-ups, I have to keep training myself to remember they're there and look for decent opportunities to use them (not waiting for the uber opportunity-because you usually die with it in your hand--I laugh every time a dead opponent drops and unused bubble shield).
When it comes to regenerators, don't be afraid to take them on, you just have to make your damage quick. Headshot snipes, one-shot shotgun hits (the kind that drop you), assassinates, stickies, basically anything designed to be a one hit kill will still kill them (if you're dead there's nothing to regenerate). If you're not strategically positioned enough to do any of these, lay low until help comes and try to tag team him, or better yet, leave him there by himself and acquire new targets.
On Last Resort, don't just use the grav-lift for getting onto froman, it's awesome for getting onto seawall undetected (from the br spawn hole looking out onto froman). A lot of people haven't seemed to pick up on that yet.
maybe you'll get a grave kill, but if you throw grenades before the end, it'll cost you and lessen your chances for the kill.
