For any bike you should take a tire repair kit. bead breaker, tire irons, tube or tubeless repair kit, some way to inflate the tire. Then throttle cables and a clutch cable. Then it depends on the bike, model, year, mileage. If it is a new bike, break in in gently then do a shake - down ride for a couple of thousand miles. Then a major service then go. If it is a "older bike" go online to "The Internet BMW Riders" www.ibmwr.org
or for old aircooled boxers "The Airheads Beemer club www.airheads.org
Find out what breaks or wears out on your model and replace the suspect parts before you leave. Whether is needs it or not.
Example, R100GS - replace drive shaft and needle sleeve bearings in paraleaver, alternator and brushes.
You can not guess what will break, you can be sure that the parts that usually go bad are new and probably have a year or two (20,000 to 50,000 miles)to go.