Well, you got to feel it out I guess. Usually it helps me avoid hitting my shoulder when you tuck your chin towars your opposite armpit. Your hands should be pushing you into the roll a bit, and for me it still varies on how I place them. Sometimes you have to put the hand, in this case my right hand since I roll from right shoulder to left hand, a little bit back from the other one in order to get that angle, or if it helps instead of placing it facing forward make one hand (or maybe both) face inwards toward each other ---> <--- like that with your fingers.
Mostly it's the chin/head tuck that gets the back of my shoulder exposed and it makes it easier to rotate so you don't hit the vulnerable parts.
That's mostly the "roll" part of the roll, I guess
. If it has to do with getting out of it right, getting into it, etc., then I'll try my best to help. My rolls started getting consistent a couple weeks ago, so I can empathize
