Well, since we're both Barra guys, I think I know your pain.
But you could give us some details: are you having trouble when they pass? Or is it when you're in their guard? Personally, I only started having trouble with chokes since I started playing the Lockdown. But Eddie says it's alright to get choked at first, so I'm confident my game will improve (even though we only have one no-gi class a week, I'm trying to go 10P with the gi)
Now, in general, you'll always want to check their grips. You're in their guard, they got a deep collar grip, posture up and check that grip. If you can break the grip without them breaking your posture, even better.
If you're getting choked from the half-guard or from side control, you can work your hip escapes - this way you can loosen the pressure on your neck. Also, "looking to the other side" is a good way to loosen the pressure and create enough space to survive and check.
Now, if the guys are trying to choke you from inside your own guard, Armbar City.