@Ayylmao Online is its own experiance. I'd say finish the story first, as GTA online requires a certain amount of set up and initial decisions to be made with start up cash. Its also best if you have friends. Friends are good for match making heists, which is the main way to get money before cheese. And they've probably patched the cheese.
Honestly I'd advise against playing online, online. Initially when you go online, just stay away from people, and if someone comes near you with malicius intent, open up Resource Monitor, right click the process and suspend it. It will eject you from your instance, but keep you online. This is such a known exploit that nearly everyone elses it to dodge trouble when on certain missions.
Also, when you first play you will be asked to get a car. Spend as much time as fucking possible running around on foot to find the best car you can. Why? Because you can upgrade your initial car at a garage for FREE. This is otherwise expensives as fuck.
