The best way it's to choose something you know and like. So, if.you like some sport choose sport betting. If you are good i stategic things choose poker. In any case something that goes along with your character and interests.
Gambling at first should be fun, don't chase the money at any price that often leads to the dark side. Plan in advance funds you can spend on.gambling and try not to go over that line.
Indeed, the most common mistake players make is that they think of making money through gambling (which is mathematically impossible) while this is just entertainment. And to have fun here you have to spend money. If everyone understood this, then there would be less of these tragic stories when players lost all their (and not only) money trying to win.