... that organizing closets, or anything, is very similar to designing a web site, or a garden, or anything else. Your first step is to decide what you want to keep in the closet. Then you need to get a paper and pencil and sketch how you'd like to see the closet look.
Items to be stored, because they are not used daily, or even monthly, like wrapping paper, can be put up high. Things that you use daily, like towels, bed sheets, etc, need to be down low and accessible.
I know one woman who took the doors off of the closets in her children's rooms. She then placed their dressers inside the closets. Still room to hang stuff on the side, and more room in the bedroom! I would love to do this, but my dh thinks it's weird!
But, once you sketch out how it should look, go to a local home building store (around here we have Menards and Home Depot) and check out their closet organizing materials. Measure your closet first, so you know what size you need, and buy a kit first. Then you can add on as you go.
My question is: How did our parents manage without these closet organizers??

I look into my unorganized closets and I think "what a bunch of wasted space!" (See, my home is far from perfect, but don't tell anyone!)
Amanda, I've seen your home - you have it easy since you have moved so much ... you hardly have any
stuff! My home is about as organized as yours, only I have 14 years of accumulated
STUFF!! 
We've slowly started to dig out, though. It's almost liberating!
Kelly H.