Blindly heading to the mall with the generic task of "back-to-school shopping" in mind is a surefire way to spend more than you planned, says Marino. Instead, make a list of the specific school supplies that you'll need and seek those out -- you'll be less likely to fall victim to impulse purchases.

If your kids are old enough, consider setting a clothing budget before you leave the house and letting them choose the items that they want to spend it on.

"When they agree to the pact, it gives them boundaries they are more likely to not fight and (to) work with," says Susan Tordella, author of the parenting book "Raising Able." Make sure they know ahead of time that you reserve the right to veto any items that are ill-fitting or inappropriate for school.

For shopping trips for school supplies, you may want to venture to the stores alone with each child's school supply list, says Nelson. It's easier for you to ignore the "designer" folders and unnecessary products that lard the shelves and can bring up school supply costs.

"We can definitely save money by buying supplies on our own because we probably won't give in to impulse buys," Nelson says. "Your kids may say, 'Oh, Mom, I really need this special electronic pencil-sharpener thing.'"