Sorry to say: There may be practically no free credits in your country.
Only in the US, Canada, UK and - perhaps - Australia there's possibly enough of these offers. If you find them, you'll quite often find yourself feeling scammed because they may not pay out voluntarily.
If you don't find those "free" offers, don't wait for them to come - you will be deemed outside of "useful" markets, like we are in Germany.
In these cases it's best to rely on ourselves, find different resources.
I for one think that it's best to take the money that I earned to finance what I want here. 10 - 20 $ per month are sufficient for some fun - less than every other entertainment that I seek outside.
Don't rely on hope too much - hope is futile here ;)