Some fantastic suggestions in this thread! Sorry I didn't get to it earlier.
I don't have great experience with starting sites from scratch as most of my sites are properties I've purchased, but in managing and working on those sites over the years I've come to appreciate the thought went into the planning. I would suggest focusing on what you do have rather than on what you plan adding later. It makes your site look "complete". One thing I would say is that you should focus on the reader, not SEO. Various fads have, over the years, messed up otherwise good sites. For example, at one point it was believed that Google ranked pages higher if they were in the root directory rather than buried a couple of folders down. It ended up with one site I bought having over a thousand pages in the root directory many of which should really have been organised in folders.