How do you sort your LPs?

By genre, first, but in the classical category I just finished sorting by the labels.  Within the labels I have a good idea of the artists, composers and pieces.  I guess I'm thinking of selling down the road as I'm getting older and wanted to see if I had anything valuable.

Genre, then alphabetical order....for example, jazz, blues, rock, disco, military marches, soundtracks, disco, easy listening, classical, country, folk, etc. Have MOFI separated on their own racks, as I do Nautilus, DCC, Simply Vinyl, Etc. It’s a long process and is still something I am trying to keep up with, but the occasional flea market, record store, or on line purchases are accumulating faster than I can sort. And, coworkers, family, and friends who have given me boxes of records, I am still sorting those as well. In Germany, my old neighbor gave me a box of classical Deutsche Grammophone records. 

Just make it easier on yourself and not over think this and just do it alphabetical.

while you are at it....make a spread sheet of what you have also and can update as you add to the collection.

Alpha.
Genre is too hard as Eric says, too many artists fall into possible 2 or 3 genre's depending which way the wind blows.

I suppose it also would make a big difference according to the size of your collection and how often you add to it.