The best thing you can possibly do before your photoshoot is to get a good night's sleep.
Getting a good night’s sleep will not only keep you looking your best but will also keep you functioning at your best so make it a point to turn in early for the night and aim for at least 8 hours. Stay away from all electronic devices. They’ll only distract you and studies have proven that the bright light emitted from them actually trick our brain into higher levels of activity. So pull out a good book, or a boring book and read a bit, this will help you fall asleep and be ready the next day for your shoot!