This would be the best way to earn Bitcoins: Get a job and take out 10% of your earnings and spent them on Bitcoin. It always works for me 
10% of your income is not bad considering many people do not earn over $100,000/year, which equates to less than $10,000 invested in Bitcoin. That has a lot of potential to grow, considering the very low prices of Bitcoin right now. Great time to buy Bitcoins!Indeed some invest even more then 10% and wait for the right time to come and to withdraw and get some more cash.
Some other post have been out of this topic but no worries.
It really depends for what amount of money are we talking about. If we talk about 1 million then 10% is huge ($100k)
One of the best way is to invest in good start-ups and the profit will come.