Make sure you take the time to get all of your paperwork in order. If the offer was made to you verbally, make certain you also get a written offer. The basic information you are looking for is the salary (plus any promised bonuses and/or commissions), start date, and who to report to and when. Treat it like gold since that letter is an actual contract—but remember, not until you accept it. Make sure you put your acceptance in writing and keep a copy for your files.
Ask if there is any employment paperwork you can fill out before you actually report to work. Taking care of your paperwork now will avoid confusion later. Make sure everything is in order now and don't put it off.
P.S. Most banks will acknowledge your offer letter as sufficient for securing a car loan. So if you have been waiting to buy that new car, you now have the necessary document in hand.