Add detail to boxcars with open doors.  Add some crates, boxes, tarp load, or figures to your boxcars that have open doors.  There are even lumber, barrel, or bag loads you can place into an opened boxcar.  You can even add a fake wood flooring to add more detail.

It's said that people who live with a pet being to look like each other. I wonder if it's true with layouts?

After a little advice with where to start, [ ... ]

For the TL;DR - just scroll down an look at photos is useful since it's about architecture :) Feedback appreciated !

I want my layout to have a high level [ ... ]

I've read lots of advice, howto, intro, and helpful things on the internet about modeling railroads.

But nowhere is there any information for the beginner, [ ... ]