Take care of any business before you go in so you can keep your thoughts on the task at hand. Having said that, be prepared for anything and have fun.
Recording is the best part of the whole process of record-making.
Take breaks often as you ll feel better as the days wear on. Above all, trust your producer . . . When I m busy working on a record, I become so focused on the task at hand that all etiquette and manners that my mother taught me go completely out the window.