I have some investments in bitcoin casino, i made 5-10% profit / month 
Nice! 5%-10% is a good percentage and profit for a monthly basis with bitcoin casino's. And that is what I wanted to suggest, you can try to invest with bitdice.me
But the most effective and best way to invest in bitcoin is by just simply buying it at lower price which is quite hard to make it happen again.
The new low price for bitcoin will be at $1,000.
Investing in bitcoin is best way of investing. before investing on something make sure you have best knowledge of the market, then save the btc which will give you best in return. best place to investing is nothing better than btc. just compare the investment value with any other way of investments, it is much better investing here in btc.
Yes and bitcoin itself is an best form of investment so if you are looking to invest your fiat in something then right place would be to invest in bitcoins and it will give you best returns in future in compare to other investment products.