The best way to make money is 100% an iron farm. If you want to get rich fast, here's a step by step tutorial:
1. Making some starter money
Use IGPs like /pw blockIGP to make your first billion dollars in a couple of days. Also try selling rare items or making large builds and then selling them for a good amount of money. I think a good amount of starter money you can make from this is around 3 billion dollars.
2. Start building an IGF (iron golem farm)
Ask professionals to build you one or just get a blueprint of an already built one. Wanna know how I built one? I found an already good iron golem farm, asked my friend to use Litematica (which is a schematic mod) on the farm, and he built it for me. So just use a schematic mod on a different farm then build it, otherwise hire someone else to build it for you. ALSO IF YOU ARE COPYING ANOTHER FARM, ask the owner of the farm how many iron golem spawners it has and how much money it produces every 24 hours to see if it's good. Use this calculation method to check if the farm is good:
Total money per 24 hours ÷ total spawners = iron rate.
The iron rate determines if a farm is good or not. A farm with an iron rate of 100,000 or above is a food farm. Below that isn't so good. My farm in its prime peaked at an iron rate of 666,666.667. It made 2,000,000,000$ per 24 hours with 3000 iron golem spawners, which is the highest iron rate I've seen (no self glaze). Most farms don't produce that much money and only produce 300-400 million with 3k spawners but idk, maybe my farm was just built different.
3. The spawners
When you are buying igs (iron golem spawners) always try to buy cheap spawners that are 1.5 million $ or less. While setting up your spawners in your iron farm,don't set them up randomly, try asking someone a good igs pattern first.
4. Afking
Your igf is done, now hire someone to afk the farm and you will start getting good money.
