I tend to upvote a post when it Links an interesting article or provokes an interesting conversation, and only downvote them when they voice an convectively bad opinion (like, bigotry or other unjustified vitriol).
I tend to upvote comments when they make a good point or at least try to support their argument, and only downvote them for the same reason as posts: when they are trolling, being unnecessarily aggressive, or trying to justify bigotry with fallacious reasoning or something
What about you?
Ah, I suppose I can be a bit more specific about my process.
Posts: upvote if I care/liked it, downvote if I don’t care about the post so I will hopefully see more of what I care about, and less of what I could careless about.
Comments: upvote those that add value, and really only downvote those that specifically subtract value (mostly when people are being jerks)