Dxrkwave

Greetings Im very new to Rockstar Games, and I havent played the first RDR. So my knowledge of the game mechanics and functions is very newbie. All though I managed to complete the main story line of RDR 2. But there is one problem which is that I dont know how to earn lots of money after beating the main story. I have been robbing and looting people and you get some but not that much. Is there someone here willing to help me understand certain things? Thanks in advance kindest regards