Cobra is uselful in that at least when you hit the 'waaaahhhhh run away' moment you'll actually be able to do it.
Low CZs are worse than High ones in my opinon because you get less support. Go to a High CZ, drop in and boost maybe 10k away. Then and only then, pick your side. Head back in, stay close to grouped friendlies and pew pew. Make sure you watch the radar - at some point in any CZ you'll notice the balance has shifted and you suddenly only have two buddies with you vs 8 enemies. That's when you're happy to be in a Cobra. Run Forrest run. Also if your shields ever look like they're about to hit one ring left, it's Forrest time. In a CZ you don't have to kill everything yourself so don't try to - treat it like a high res and attack your allies targets to help them finish them off and hoover up the combat bonds.
The single biggest skill in a CZ fight is knowing when to say 'OK that's enough, not worth risking these bonds for another kill' and getting the hell out of Dodge. I say that as someone who has previously reached that epiphany 20 seconds later than I needed to on several occasions.
This is excellent advice.
Some other advice I will add is:
1. Outfit that Cobra for combat, i.e. don't take a bunch of crap in there that you don't need.
2. In CZs, shield boosters are your friends. Personally, I don't think you have to wake when your shields get down to one ring, but you should definitely be putting space between you and the bait ball. (YMMV)
3. Your really, really good friend is the HRP. Use your internals to stack low-weight HRPs (4 1D HRPs are better than one 3D HRP... the offer more protection, but weigh the same combined as the big one).
4. Offset the weight of the HRPs by downgrading your fuel tank and FSD. You're not going to Sag A, you need enough fuel and range to escape-jump out to the closest system and back again.
5. Before you enter the CZ, pre-plot your closest system jump. Keep this on standby (you can keybind it) so that if you get in trouble, you can bug out without mass-lock hassles.
6. Know when to quit. Once you get the hang of it, run your sorties in small chunks. 100k is about my threshold. I then wake out, turn in, and prep for the next run. (Red Anders already addressed this)
All I have is an A rated Cobra III...
And don't think this way. The Cobra III is an excellent CZ runner, as long as you fly her properly. Easy rebuy, too, if things wind up going badly.