Remember that flexibility is important in the design of your teenager's closet, especially if he/she still lives in his/her childhood bedroom.  That way, every time your child reaches a new milestone of maturity, you can alter the layout of the closet.  

If footwear is an expression of identity, then expect that your teenager's tastes will constantly evolve.  So make sure to outfit his/her closet space with shoe shelves that proudly display everything from combat boots to patent leather Mary-Janes to Nikes.  

Adjustable drawers and pull-out shelves are key to accommodating the changing needs of your teenagers.

Slat walls and hooks are perfect for hats and accessories.

If your kids clamor for bathroom time every morning, then consider adding a vanity area to your teen's bedroom or closet .

Include laundry baskets in with multiple liners to encourage teenagers to sort their own laundry.

If your teen has a leaning tower of stacked CDs, then ask him/her to gather his/her favorite 20 to keep next to the stereo, while the remaining collection is stored in either a labeled container or a storage unit designed specifically for CDs.

Have your teenager evaluate each item in the closet and then ask him/herself: How long has it been since I've used this item?  If the answer is "forever", then either purge or donate it.

If your teen is especially sporty and owns large, cumbersome equipment, then place such items in storage bins with rollers for easy access.

First things first, teens collect an endless variety of stuff, so any closet make-over benefits from removing every single belonging, even the forgotten ones stuffed into the darkest corners.  Once everything is out in the open, classify your teen's items for better closet organization: hats, jeans, jackets, shirts, shoes, old toys, etc.