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.

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, [ ... ]

     Since NOBODY will be reading this I guess I can vent here. 

     Same thing other people have griped about in [ ... ]