Right foot on the floor, lower myself in at an angle to clear the roof (and if in a tight parking space, sort of sideways as well), then pull my left foot inside when seated.
To extricate myself, it's a matter of a reverse of sorts. Left foot out, left elbow on body, and push myself up and out. Not elegant at all.
I've been trying to get into the habit of swinging both feet out then standing up (with a little push on the door sill), but it's been hard to remember to do all the time.