My first question would be how many miles are on the car? Fresh gas would be a must as well as an oil and filter change. Replace the air and cabin filters, have the battery tested, check the condition of the coolant and prepare to flush it. Expect there to be some flat spotting on the tires. You may want to replace the tires if there are flat spots and if not, at least have them balanced. You may have to reinitialize the TPMS, so prepare for that quickie. I would go through the brakes and replace the pads and rotors if there is rust buildup on the rotors. I have read that BMW rotors should not be machined. You will also want to have the brake fluid flushed when servicing the brakes. I wouldn't take any chances of moisture buildup in the fluid. I would also take the time to service the caliper brackets and check the parking brake. I would then check for any abnormal leakage and run the A/C and heat. Cycle all of the electronics to ensure everything is in working order and that corrosion did not build up or mice did not make their way into the car. That's just personally what I would do.