Have your hair done the day before the photo session and wash it on the morning of the session.
Remember that striking eyebrows, nasal and facial hair and ear tufts can be exaggerated in close-up facial shots.
For women, too, facial hair - however fine and blonde - can show in close-up shots.
If you think that your armpits will show, shave or de-hair the day before. The same goes for your legs.
If you are planning to pose nude or in lingerie, you may want to trim your bikini line. If you normally shave your pubic hair or sport a "Brazilian", shave, de-hair or wax the day before to prevent stubbles from showing.