Does anyone have advice about improving my karma? I'm roughly 42nd percentile. I suppose lurking doesn't help.
That is, just post your thoughts on a topic, written as best you can. At least, that's worked well for me and probably most other high percentile-ers. Don't start pandering to what you think will attract a lot of upvotes- karma is meaningless after all.
Commenting at the right time seems to help.
Having a single thought per post also helps; people tend to upvote if they agree with the entire post.