Get some friends to do some drug runs with you. Be armed, in case someone tries to rob you, and pay attention to the cops.
As @Ray said, doing meth runs is pretty good pay, but it is risky, specially alone. There's nothing as frustrating as wasting 45 min gathering drugs just to get caught by the cops or killed by someone else.
Also, RDM (Random Deathmatch) is very likely to happen in the bigger cities (Kavala, Pyrgos, Athira, etc). Make sure you setup a way of recording your footage, so in case you do get killed without initiation, you have proof of the incident. Then post a player report so that the offender gets action taken against him and you recover what you've lost.
Feel free to msg me if you need anything!
Welcome to Asylum