We do 36 hour shifts, which I truly Like the best. I have worked the 24/48, the 48 hour shift, and the 12 hour shifts.
Now go in, introduce yourself, most likely you will be a third (I am guessing) So your partners should do a little introduction type thing for you, and show you what needs to get done. Rig Check is number one priority. Another thing is clean up after yourself. If you make a mess, just clean it up. Depending on how your partners are, you might be eating out, or you guys might make meals at the station. We split meal cost when we make food at the station. If possible, try and grab a nap when you can. If your partners are doing things around the station, is probably not the time to take the nap. I know Bueno said no naps between 8a-8p, but if you can grab a quick 30 min nap, get it, cause you might be running calls all night.
Coffee is a major thing that gets a lot of crews through shift, if you do not know how to make coffee, than I highly recommend googleing that.
Second uniform is always best, bring your own bedding (Usually sleeping bag) and dont forget about a pillow.