So, in general, I mod up. I like to think of myself as a positive person. Occasionally, I'll see something egregious and mod down, but that's pretty rare - Something I do only slightly more often than I use my horn out on the expressway, typically 3 or 4 times a year.
What I wish is that there were more mod categories. I'd like to combine some to make new ones. For example:
Insightful + Funny = Ironic
Insightful + Flamebait = Controversial
Offtopic + Troll = Inane
I'm sure you can think of others.
I'd also like a Sarcastic mod, but I can't decide whether that would be +1 or -1. Along with that would be a Pedantic. Definitely a -1 there. And, to end on a high note, I occasionally run across posts that actually rock my world - I'd like to mod those Enlightening, +1. Kinda like Insightful, only up a couple of notches.