If you're not fully immersed in it already there is no hope IMO.
There's too much stuff that has been added and everything is so expensive you'd be grinding through countless boring missions for weeks just to get on the first couple of rungs.
It started off fine. Everyone started with a stolen vehicle and a 2 car garage and the majority of people were roughly the same level. Now you've got people with multiple properties with 10 car garages in each, offices, motorcycle clubs, bunkers, warehouses and an array of OP vehicles.
I still play online and i'm a decent level, 250 something, and if i'm not in a mission I'm permanently in passive mode because i'm way behind the top level people.
The snow is cool though so have a ganders over Christmas. Usually starts Christmas Eve.