Are you trying to organize the bathroom?  You don't want to waste or lose any valuable space, but extra deep closets and cabinets create a unique dilemma.  Try these tips for utilizing the space you have.

1.  Clean out the space.  Pull out the towels, soap, razors, shampoo, nail polish, toothbrushes, etc.  Go through every item as you pull it out and put each item into one of two piles: Keep or throw away/donate.  (Really now, lotion from 2 Christmases ago... throw it away!)
2.  Sort the items into groups -- soaps, travel products, medicines, first aid supplies, pet hygiene items, hand towels, fancy towels, shaving accessories, seasonal items (such as sunscreen and bug spray), and the like. 
3.  Once you have accumulated separate piles, decide how you want to store the items-- do you need daily access to it?  Don't store it at the back of the shelf.  Remember: you do not have storage containers yet! 
4.  Measure your space: each shelf has a width, depth, and height.  On the same paper that you're sketching the closet and measurements, mark which shelf will be holding which products, plus note the tallest height of any products that must stand upright.
5.  Go shopping!  Some of the best places to look for containers: Walmart, Target, Dollar Tree, Kmart, Container Store, and Bed, Bath, & Beyond. 
6.  While you're shopping, try to follow a scheme.  If you are using plastic tubs and clear shoe containers, try to purchase all white or blue containers/lids.  Baskets should have the same shape and weave color. 
7.  Put everything back into the space.  It might take some reorganizing over the next few days as you start to see what's used on a regular basis.
8.  Pat yourself on the back for making one space in your life less cluttered!

There are a lot of unique containers available out there.  Over the years, I accumulated a variety of containers
and didn't want to start from scratch.  What worked for me was to pick my scheme (white plastic tubs) and put everything else to the side.  I had metal round baskets, low wicker divided units, pink plastic tubs that stacked, and so much more. 

The items I used on a daily basis went to one pile, and everything else in another.  I put seasonal items including bug sprays, sunscreens, aloe cream, and summer-scented lotions in a rectangular metal tub behind the towels.  This keeps my towels from getting pushed all the way to the back of the shelf (out of daughter's reach), plus no one sees the basket buried behind.  I put my husband's hair cutting kit on the very bottom shelf, behind a tub holding his pomade, mouth rinse, floss, cologne and deoderant.  He only cuts his hair twice a month, and the tub goes with him in to the bathroom each morning. 

For all of my stuff, I needed more than one container!  I travel overnight often for work, so I put all travel products in one tub.  Then I put all of our extra purchases (toothpaste, lotion, etc) in another tub.  All of my nail polish, nail files, and cuticle devices stored in another tub.  Special occasion make-up (ladies, you know what I mean) went into another, and feminine products into a separate one.  The feminine products went to the back (how often do I need them?) as did the nail polish tub.  Then the extra purchases tub and special make-up.  Up front I kept my daily needs items in open-topped containers with a basket so I could grab it on my way into the bathroom each morning. 

We cleaned up our closets because our house went up for sale.  We moved across the country, and while searching for a new home lived with my parents.  We utilized these same tips on my parents' house, only to figure out they were wasting a LOT of space!  Less clutter in the closets for them meant less clutter out in the open elsewhere in the house.  It took us two and a half months to organize all the closets in the house, but getting everything put away reduced the household chore time by HALF.  That and we had a $1,200 garage sale!  :)  What's your next project?