Starts with a program requirements submitted by the client
Then I think about a general concept..."The project MUST to be", "The project MUST to have", "The project MUST to show", "The project MUST to achieve", "The access to the building MUST be here or there" ... Note that I'm saying MUST.. I never say I WANT the project to have, to show, to achieve, to be... it's not about I WANT, It's about the project NEEDS and that includes a construction budget submitted by the client too.
Following that, Zones.
I organize the areas, in floor plans and elevations. Every need have an space to be satisfied. And spaces can be grouped.
Then I sketch a basic scheme with areas, spaces, halls. I Detail everything, I think how can the project get better the environment, interiors, materials. etc...
Till this point, everything is just freehanded. Not a drawn lines.
After that, I Draw the floor plans and build a 3D model.
In all this process I drive an style (Modernism, Minimalism, deconstuctivism or another, I prefer minimalism) but I keep in mind the client likes could influence in shape language result of the project.