we dont' really do alot of technique specific warmups, but sometimes i will have guys do this:
starting from guard, bottom uses a sweep (scissor or pendulum or hip bump, one sweep is assigned for a certain number of reps) to go to mount, mounted person now uses a mount escape to get back to guard, repeat for time or reps. i like that sequence alot, because it is a good flow, and gets you used to escaping mount and immediately looking to sweep.
as far as concepts, on the sweep, i emphasize controlling posture, and creating space, on the escape, i emphasize immediacy of action, the sooner you start your escape, the easier it will be, the same with the sweep.