1. Check autofocus and exposure - Take a shot and check.
2. Check flash - Take another shot with flash
3. Test for buttons - Press and turn every buttons and knobs and make sure the LCD shows the appropriate changes
to be honest, most dslrs do not need local warranty of one year only. one year is hardly the time when problems develop. if problems develop they generally do so quickly, in which case an exchange with the store would have been done.
in any case, different people have differnet levels of tolerance. i usually buy grey because of limited budget. so far, nothing went wrong. but if you do not wish to take the risk, then best to buy new.