Some tips:

Move Your Head to the Side When you Bridge
When you bridge –
Move your head to the opposite shoulder. If you bridge to your left, put your head on your right shoulder.
Bring your feet to your bum so you can raise your hips as high as possible
I slam my feet into the floor to get a reaction force
Throw your right arm (if bridging left) into his ribs as you bridge or push on the ribs
Bridge again and push /frame on the elbow if guy bases out to the side, or go into a hip escape.
You can frame on the elbow and try and move yourself out from underneath or push him again with another bridge

Have a default mount escape to go into immediately on being mounted
Don’t let the guy settle into mount. I bridge then move to hip escape straight away.

Chain your mount escapes:
I can’t find a very good video as an example, but I like
bridge to hip escape, to ‘hip hop’ escape, to the ‘shakey bench press escape’:

Hip escape:

Hip Hop Escape: