When you have made a few trades start increasing the capital.This seems to be the best method
making bitcoin on idle are also good if youre a busy person or dont have any idea on any investments then you should not do anything on your coins which is much safer than investing on things that you dont have any idea at all. 12 bitcoin is already a huge amount and we should not risk or do some thing that it would be wasted.
Invest those coins in something only if you hold good knowledge of it, and if not then do not experiment with them and simply hold them for future to get safer profits from it.
Its better to hold than to risk it with some investments which you dont have any idea or you are just experimenting and for sure you would lose your money on that manner. Holding would not hurt you instead you could still be profitable on long term because bitcoins price is rising.