A debit card uses funds from your checking account.  If you use your debt card and don't have the funds in it, it's possible that the transaction will go through and you will have an overdraft fee.  There are several reasons why the transaction gets approved. 1-The banks let the transaction occur because of the relationship you have with the bank.  They think you should know how much money you have in your account and if you want to overdrft it, it's because of an emergency. Or a check could have cleared around the same time.  Bottom line, if you don't have it, don't spend it...it's YOUR money.  As for perks, some banks have perks for schools (WaMu),  airlines, Bank of America has Keep the Change, airlines, Nascar points, MyExpression Banking which you earn points for team gear, etc.  Also, most banks charge a fee if you use an ATM machine that is not from their bank.  So choose a bank that is near you and where you travel. 

Credit cards were described fine in the previos statements.  Keep in mind, it's usually the better the rewards, the higher the APR.  Find out when you could start redeeming points.  I have a card that redeems points at 2500(BankAmericard visa).  I had a card that rounds up the points to the nearest thousant.  Example, my airline ticket was $667 but Capital One used 70,000 points not 66700 points.  Plus redeemation starts at 10,000 points.  If you plan on traveling outside of the USA, there is a 3% foreign currency fee on Visa/MC.  Amex has 1% and has offices n many large cities around the world.  But bring both cards with you because AMEX is not as widely accepted as Visa?MC.

Good Luck