I think the best way to increase the bounty earnings, is by participating in many promising projects, and doing the most paying campaigns, like the translations, the content creation, and the signature campaigns. This way you get a high number of tokens from each campaign, which you can sell them later at a good price.
Find campaigns that have limitation in participants since too many participants loses the chance of earning more. It's hard to join in translation if we don't have good portfolio, content creation will be good to go as long not fits on criteria.