Trading for sure is the only way to achieve that target otherwise it is too hard to get that amount in a week, though someone can do it also with skill works but for that he would have to work very hard everyday of a week to get that much in a week.
Yeah trying many ways can help to achieve that 0.3 btc a week like doing some trading and investing on trusted sites and also trying some freelance that is related to your skills. I think it would be easy if you just don't focus on one thing.