There is no safe method. That said you can try betting a small amount but you will lose in the end. Its the casino owners who make a profit and the players are the losers.
If gambling was a safe method to earn money then people would not study hard and get jobs to earn money.
Yes, Gambling should not be considered as a source of income cause It doesn't guarantee that you will earn from it. Just gamble for fun and only use your extra money
Although it is not a guarantee but you can try to earn something if you have good amount though. Huge balance and try to aim around 0.01 and that is easy for someone who has big bankroll. And in a month you already can earn 0.3 and that is good number though