I'm working on a storage shed that could eventually become a workshop or tiny house.
I started by clearing the site and marking the foundation with a stringline and level. Poured concrete footers with cardboard tubes, and embedded a bent 9" section of 1/2" threaded rod in each corner to lock everything down and together. The entire floor fit in my car. I screwed and glued (polyurethane glue) everything together and bolted it down.
I did "yakisugi" (Japanese wood burning) on the exterior frames and parts of the longitudinal "beams" (2"x4" by 15') and purlins that would be outside. I also precut scarf joints for the 15' purlins and beams. It took two pickup loads to move all the framing, floor insulation, sheeting, roofing, and more....
Mineral wool insulation on the floor. Stain on the 3/4" plywood floor. Sides and undersides primed with "Extreme Bond Primer."
They gave me the last of the plywood boards from an old stack at the lumber yard. Two or three boards were in bad shape. I pulled the warp out of one by screwing in a butt block. I used the worst pieces as temporary doors to button everything up.