As a physical therapy student, if you know you're going to be lightheaded/dizzy when you stand up, I would recommend doing some ankle pumps (like you're pressing on the gas pedal), seated marches (lifting each leg into the air while seated, one at a time), and/or leg kicks (kick one leg out a time). This can help get your blood flowing and (hopefully) avoid such symptoms from standing up. A squat like OP recommends probably works fine too, but my concern is a risk of falling over and maybe getting hurt if you get dizzy then do a squat. Depends on your symptoms and condition of course.

Also if this is happening to you all the time and it negatively affects you, please consider going to a Physical Therapist or your physician to get it checked out!