I would plot the layout, etc of the shop first for what you might by. Thus plan out the storage, electrical, and so forth, so when you buy stuff, it fits into a plan.
Beyond that, let the projects drive it. Generaly, if you are starting out, project will match the order of construction, so working from rough framing, to eventual furniture. Buy tools that match the flow of projects. There really isn't a need to buy tools now for fine finish work if you won't be doing that for many years. But if you will be framing walls and such, buy a miter saw.
I would also hatch a plan. Do you want to have a flexible shop, mobility, one person movable, etc. And plane out tools, and how they interact. Some things like just buying all Festool for example, would make dust collection straight forward, but if you will have big stationary stuff, I would think you want to plan for some standardization of things. Similar for power. Do you want to be all 110V, or do you want to be 230V. You very much can buy tools from all sorts of companies, don't get trapped in one brand, but planning some ways they interact better with each other can help.
All that said, without knowing anything else, a 12" sliding compound miter saw is pretty going to be the start point for many folks. Unless you want to go all out on a push/pull table saw.
Biggest thing I would say is, dust collection. Plan everything around dust collection, don't buy any tool that isn't good at dust collection. A festool dust extractor is a great bit to start with.