The best way to earn bitcoins is by working a day job and converting your fiat into bitcoin.
Other than that, it requires you to have money to invest in things to buy and sell.
Investments and gambling are surefire ways to get rid of all your bitcoins.
Yes thats right having a job is the best way. Work for it and don't hope that they gave you a bitcoin, because theres no free in this world all the things that you want must you hard work for it.