In the build editor there's a button for uploading the station's construction plan - you're supposed to do that here.
My stations rely on snapping so the amazing radial designs that others use are not part of my build plan - I value being able to move the entire station from the first module and that needs snapping.
Here's my Cliff's Notes:
Symmetry. Whether snapping or not, work out lines of symmetry in advance. I use a greek cross for my templates and put the basic connectors and docks down before adding storage, habs and production. This gives me a cube to build in which is efficient use of space, and my designs have examples of using the vertical element too.
Rotation. Storage on all sides > then; Raw Materials > Intermediates > Products > Food and Medical on the four sides.
Habs and docks > Top.
My Milspecs do use the bottom for defences.
That's for Community goods.
My Terran builds use rotational symmetry. Since Terran modules boil down to energy, three construction materials, intermediate agricultural, food and medical, they might have only one kind of material on each side, or a mix of them.
So first build a design scaffold.
Then add storage and energy (profit bootstrapping!)
Raw resource, intermediate and final product; food and medical; or for Terran builds a mix of everything, or your station focus.
Habitats.
Defences.
If you want sections built in specific orders, you can remove and reattach entire chunks of station. This adds them to the bottom of the build queue, so you'll need to also reattach anything you want built after the moved piece.
That's it. Don't expect a station built around what you need in the moment to be an architectural triumph - if you want it to look good you need a build plan.
There's one more thing. If your station is supposed to be completely or partially self sufficient you'll need to know how much of what to build. The game itself has no self sufficiency calculator but there's one online! It even factors workforce bonus. It's there at a Google search, but I can link if for some reason you need it.