Wellcome,
I think you should prioritize to participate in the translation program it will be very good for you to help you improve your English and earn more income.
If you have a lot of followers on FB and TW channels, join the rest
Some things about the bounty program
1. Youtube- making videos to promote their projects.
2. Blog- making creative content about the project to promote it.
3. Facebook- Like and Share/post their post in social media to promote them.
4. Twitter- Tweet/Retweeting their post to promote them.
5. Translation- Translating their campaigns to your native language.
6. Signature- Wearing their signature and making their required post to promote them.