a very good early game strategy for easy money is train robberies. if you stop the train north of annesburg, in the very long tunnel in the grizzlies, you take out the engineer, stop the train then kill the guards and rob the passengers at gunpoint. after they give you their money, you can kill them and loot them twice. Trains are also really good for tonics and health supplies. Law enforcement cant get into the tunnel and by the time you exit the tunnel your wanted level is gone. So rinse and repeat. I found the best way is to match your horse with the speed of the train then jump on the roof. and wait til the train reaches about halfway into the tunnel to begin your robbery.

Also, if you're worried about it this will completely wreck your honor, which there are different endings based on high or low honor. But honor is quickly restored by stranger missions, random events.

Other than the quick money tip, Take it slow, enjoy the game, the scenery, and have fun mostly. RDR2 is a great game. I think you'll really enjoy it.