One simple way is to use flat black on all of the interior surfaces. This includes the inner walls, the floor and ceiling. This gives them a sense of depth as well as mysteriousness. For any mountains in your landscape, use dark colors of black or brown for a better effect.If your railway track is black then you will need to de-emphasize the O-gauge that is often the third middle trail. Use the darkest possible ballast for this. Try and make your grade crossings look as real as possible. Some simple ways to do this would be to use thin black foam or even plastic strips. One trick is to take a tongue depressor and paint it the desired color and use that. This gives your railroad layout a more real look.Use signals that work at crossing. Crossing flashers and those with a drop arm combination work really well. Using as real as possible devices is the best. It works really well when it comes to impressing kids who come to take a look. Invest in a few tunnel portals. Placing these before the entrance of the tunnel can work wonders. Giving it a white washed or weathered look adds to authenticity. Use real looking vehicles around your railway road. Blackwash the grills and hubcaps of all the cars and trucks. This makes them look much more dynamic and real. If you have the patience, take the car apart and put in some dolls to work as people. One thing you never see on railroad layout models is people. Use as many people as you can as this adds to the bustle of the scene and creates an air of authenticity. Making the buildings around looks as natural as possible with lights in them as well is what will add to the overall ambiance and this increase its authenticity.