Ask HN: I want to start developing mobile apps.Any tips?

I live in SouthEast Europe(Balkan),graduated Computer Science and I work at local software company.I earn about 670$ a month [which sucks :) ].But that is the current situation in my country( average salary is 540$).I work 8 hours a day,5 days a week.

I read here about developing apps for iOS and Android and I would like to learn more about it. How to start? What tools should I download? What programming language should I learn? iOS or Android? I never did any app developing so any help would be appreciated.

Thanks for any advice. Live long and prosper:)

PS.I would be glad to answer any questions you might have about me.