I rarely experience derailments on my layout. If any occur, it's because of operator error, not the layout.
I'd think these might help ...
- Make sure the track is flat and level (side-to-side) and track pieces are aligned correctly
- Make sure track connections are tight and a smooth transition from track piece to track piece - file down any misalignments
- Eliminate S curves
- Make sure the layout has sufficient power drops to eliminate any low voltage areas
- Operate at a reasonable speed - no high-speed cannonball express
- Cantilever and fully support any elevated curves
- Run the widest possible curves you can
- Avoid running equipment made for curves that are larger than the smallest curve on your layout
- Use block/occupancy control to prevent collisions
- Avoid back-to-back switches - always put at least a small straight between switches
- Arrange your consists to eliminate any string-lining
- Regularly clean and maintain your track, switches and equipment
I'm sure there are other tips, as well
