earning 0.3 in a week without nothing , the possible way is try to look some lottery and hope you can win,, there is very small chance , but still possible to do
Well the chance for winning in a lottery is very small, it is just like looking a grain of rice in the mud. You don't have assurance that you can win on it.
So better work for a daily job that can give you 0.3 btc a week or even have a small business.
I agree that the chances of winning a lottery is too low, but there is no such daily job that can earn you 0.3btc in a week, not in internet, maybe someone can find a job that does it in real life but not possible in internet.
Only ways to do this are gambling and trading, gambling is never recommended as you can lose more then what you are willing to win in there, and trading would need a quite big capital to earn you that much in a week.