Drive a 8' ground rod next to the generator and connect a piece of #6 copper from the rod to the ground lug in the generator wiring panel. If its a permanently installed unit (Generac, Kohler, etc.), it should be clean power. Home Depot construction units can fluctuate wildly. Especially when the refrigerator kicks on. Honda portables are pretty good.
Glad you are safe and secure following this monster storm. We went through Sandy in 2012 and we were on generator for a week.