tunnels

If you've got hidden track under your layout for staging or for a long tunnel section, consider how well you'll be able to see trains and equipment in those areas. If you can, add a light in those areas to ease visibility. The light doesn't need to be on for the whole operating session, just turn it on when you need to see in there. While strings of holiday lights can be inexpensive, they can also be fragile and they can also run at a high temperature; compact fluorescent fixtures will often run cooler and use less electricity.

Install your tunnel portals before you add the plaster and other scenic materials so you can better integrate the portal into the surrounding scenery. Unless the tunnel prototype you're modeling is brand-spanking-new, you shouldn't generally be able to see every edge of a portal that's at the bottom of a cut. Plus, you'll be able to fine-tune your train clearances more easily.