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, [ ... ]

Here's video of my layout, first in near-total darkness, then in daylight. [video:http://www.youtube.com/watch?v=cLmc2DIJHkY 100x100]