You just get in the game and explore. Always check the wiki for help it's got good starter tips, it's great help for getting started. It tells you starting ways to get money and key points in city and what they're used for.
The reason people say "Find out in RP" is because that's how everyone has to start off. You RP your way around the city learning everything as you play, otherwise it wouldn't really be RP if you get told or forced to do everything a certain way. Just depends on how you want to play your character and that'll dictate how you play the game.
But a good start is always just making money through starting methods like Taxi Service, mechanic, food delivery etc, and just showing your face and speaking to everyone you see.