There is no such guide, since there are 1000 different ways to build and maintain a 15c.
If you want to spend the least amount of gold possible, making a npc village next to your cropper would be the best.
But if you really dont want to spend much gold at all, you are better off going with a regular 6c or 7c as your cap.
i clearly remember i read one though but nevermind
the gold i willing to spend on one server are roughly around 3k gold or 2 times 1600 gold top up. thats my limit tbh .
any tips how to spend wisely ?