Just simply join a signature campaign if your posts are good, it is easiest way to do that as other ways to earn that much needs a lot of skills, while campaign does not
First of all its really hard to get a spot in Signature Campaign, Users apply very fast when a sig campaign came online so its not a permanent option to earn 0.1/week yes its an alternative. Second if you get a spot you cannot earn 0.1 with a campaign you can rarely make 0.03 a week.
there are so many ways through which you can really win a good profit may be more that 0.1 BTC, one way is that if you invest your money in gambling you can ear the targeted amount in a very very short time, although gambling is not such an easy task but if you have some experience and skill of gambling with a good luck you can really make a good profit.
Gambling is not a option for gambling you need some initial amount of bitcoins to bet if you don't have bitcoins how can you bet? Also betting will make you lose.