How do you categorize your wines?

I've just started to collect wines. A few months ago, an aunt of mine who was a collector passed away and I received several cases of her wines--almost all were different appellations, vintages, etc. So, I bought a wine rack and I keep these wines--plus a few that I have purchased myself, around sixty bottles in all--in a small, cool closet in my basement.

At this point,I've got it split between reds and whites, and I can tell which wine is which by a quick glance, but I plan on expanding my collection a lot in the next few years, so I'm curious, what is the most efficient (or most common) way to categorize wines?