I want to suggest you somethings which actually help you get some profits with bitcoins by investing. Try to trade with bitcoins price, try trading with altcoins, try to invest in HYIP and if none works invest some money in gambling site's bankroll.
All other suggestions are good but investing in HYIP is never recommended, because that is a reason why a lot of people are regretting of losing their bitcoins now a days, HYIP sites are never good for investments, someone should rather try something else than wasting the money on a HYIP.