I think getting a solid nollie pop is pretty key, what's sort of worked for me is to point my popping foot so that it pops forward, rather than straight down.
I've got a different problem, but I find I always turn frontside and end up doing a nollie front heel instead.
On the otherhand, fakie heelflips are my go to flip trick, even over regular kickflips and heelflips.
Might be need more practice with straightening out and getting over nerves from previous close calls with credit carding.