I wonder why nobody mentioned cloud mining. This option isn’t the most profitable and it doesn’t guarantee fast profits but you can make more money surely. The simple rule is to invest in trusted sites like well-know HashFlare. Cloud servers also offer various discounts, so some users claim that it’s better to invest in several sites to get all possible bonuses (you can check them here, for instance: http://topminers.net/mining-promo-codes/ccg-promo-code/). There’s no the single strategy, so research and think about it on your own. And be aware of scam sites!