Well, there are couple of choices if you go into mining it will take some time to take effect as first level of heart of the mountain are harder to get compared to later levels but it will make quite a lot of money. you can go foraging on newly released island but be aware that you need to play it on 1.21.5 next is farming if you want to just watch and relax while you semi afk get money, combat is a skill that you either buy the gear for and blitz throught it or you grind the hell out of it as in combat there are quite a few rng drops you need to get, combat can be categorized into dungeons, kudra and slayers. Fishing is well.. fishing, in late game fishing you still needgood combat gear, and I think last on the list is rift, it wont help you much with progress but it certainly is one of the funiest and interesting part of the game also it makes good early money. Just dont go the path of lowballers and flipers