Gotta figure out why you want the karma in the first place. It's more fun if you don't worry about the karma. That way you can actually be interesting. Because

Gotta figure out why you want the karma in the first place. It's more fun if you don't worry about the karma. That way you can actually be interesting. Because to gain karma you have to align yourself with the dominant voices instead of being unique. Alignment makes for ideological echo chambers. So chasing karma will make you like the people that upvote your content and comment on your posts. If you look at the front page right now you should be able to see what kind of content is popular and you can submit similar content to gain karma. People enjoy debating the finer points of programming languages so that's usually a popular topic. Similarly, JavaScript frameworks and drama around that stuff is also a good bet. Then there is science and physics. That usually does well. Evolutionary psychology and neuroscience is a good set of categories to pick from. Usually articles around intelligence in either category do well. Then you have your typical startup stuff and economics/politics related topics. Those topics also do pretty well especially when there is a libertarian slant or anti-libertarian slant (because people enjoy debating the finer points of the political philosophy involved and how it helps or hinders the entrepreneurial stuff people are involved in).