drink lots of fluids, electrolyte replacement is good also like gatorades, since you pee alot when you get the iv.
Dont drown yourself with liquid, but I try to start drinking the 16 oz bottles of water 6-8 a day for 4-5 days before, during and after.
Also have the nurse premedicate with benadryl and tylenol. The benadryl puts me to sleep each time, but I dont have any allergic reactions and the tylenol keeps the headaches in check.
Remember, its different for everyone, but alot of fluids and pre medicate.