if i told you it wouldn't have been a secret no more 
but seriously 0.1BTC is not that hard to earn since it is only $63 with today's price and i don't know where you live but i don't think it is hard to earn this much money in any place if you are willing to work for it
in bitcoin however the only general way that everybody uses is trading.
I would like to know if anyone of you earns 0.1 BTC per week or even more? Is this possible and what is best way to earn it? Your experiences, suggestions and advices are very welcomed.
but seriously 0.1BTC is not that hard to earn since it is only $63 with today's price and i don't know where you live but i don't think it is hard to earn this much money in any place if you are willing to work for it
in bitcoin however the only general way that everybody uses is trading.