You can earn bitcoin the same way you earn fiat. Just instead of accept fiat, accept your payments in bitcoin. Or you can use your fiat money you earn to buy bitcoin and store them. Bitcoin is a form of currency, and no one will be willing to give away free money.
Or you can join campaigns and giveaways to get some coins and get started. But it won't be enough to cover your daily bills. Just some few dollars to spend on beers
My current signature campaign pays me around 0.025btc/week.