There are different ways by which we can obtain bitcoins like Buying on exchange, accepting bitcoin payments or using mining.
Which is the fast and beneficial resources of obtaining bitcoin??
I'll provide a somehow simpler answer than my bitcoin comrades here.
You can earn Bitcoins pretty much the same way you would earn fiat currencies. Alternatively you can earn fiat and exchange it into BTC.
To earn, you need to find a way to add value to the economy. This can be done through time or money investments... or BOTH.
You bring value to someone else = You receive some kind of compensation (unless you're working with scammers)