What should you do if at high risk for glaucoma due to family history of it?

Baseline exam. Screening eye exam and assessment of risk with followup as indicated.
Annual checkup. Glaucoma does strongly run in families. Best to be chedked by an ophthalmologist at least yearly, and more often if risk is assessed to be very high. Screening examination usually includes a peripheral vision test (visual field), measurement of intraocular pressure, photographs of the optic nerve, and a measurement of the optic disc or retinal nerve fiber layer, all quite easy and non-invasive.
Go see your doctor. If there is a family history of glaucoma, it puts you at a high risk catergory. You should have a full evaluation by an ophthalmologist.