Make sure you have Imodium, head ache tablets, bottles of water and don't order much booze. Headache/exploding butthole etc are common tactics/excuses. Bring plenty of lube and condoms. Also if she gets hammered, you don't want to be getting puke on yourself(I assume, though if you do I'm not judging. If you do , make sure it's not extra), so limit booze. Also, don't book an overnight with someone you haven't seen a fair few times.