What is the best way to reason about how to design a garden?

I am in the process of buying a house and I am trying to figure out how to do the process of designing and planning the garden. I'd prefer not to use AI (and once when I tried it gave me a lot of inconsistent answers) and not in a position to afford a designer right now. But there is so much information out there, it is hard to bring it all together into a meaningful plan. So what do you do? How do you decide which plants and where they go and how to balance all of your various priorities?