I usually style them after myself, but it's not a conscious decision. Actually, it's only something I noticed when I was making my current character.
They always have blue eyes and are redheads (never mind my avatar pic to the left - I dyed my hair dark for a while, but really hated the messy eye shadow in my eyebrows!). Got a strong jaw, unfortunately, and I usually make their chins somewhat shorter than mine. High cheekbones, which is about the only feature that betrays my Cherokee ancestry.
They're also thin, which springs from my lightning metabolism and almost complete lack of curves.
Overall, they're fun to make and I usually spend a long time on them!
Next one might be Khajiit just to mix things up.