The best way to earn a bitcoin depends on how much are you willing to invest. If you are investing starting with a low capital then mining is good for you. You can buy hashes so that you can mine satoshi faster. And if you are investing a large capital then buying bitcoin is the best way. It is because bitcoin is a long time investment and you can earn a lot by buying. It is also the easiest way to earn a bitcoin. Another is if you want bitcoin but you don't have a starting capital then you should work to earn bitcoin by joining in the signature campaign and they will pay you depends on your rank in this forum.