For many model railroaders, dreaming up and designing a train layout is just as much fun as building and running one. This process can be done either on paper or by computer.
Decide what general type of layout and track plan you want. Are you going to model a train in the old west or an elevated line in Chicago? The setting your decide upon will determine the type of track plan you ultimately create. An industrial setting will require perhaps a roundhouse and turntable along with a yard or two, while a passenger line may have long straightaways and rolling hills and bridges.
Assess the physical space you have available for your layout and draw a scale outline of your benchwork either on paper or in the program. Begin designing your track plan within this parameter.
Begin drawing your track plan using either the scale templates to ensure accurate curves and switch-track diversions or the pieces of track stored in the program. Or, you can draw flexible track in your design freehand either on paper or in the program. Be sure to take into account operational practicalities, such as the ability of your trains to negotiate tight curves, logical location of tracks and buildings and prototypical track arrangement.
Print a full-scale version of your track plan and lay it out over your benchwork. Some modelers actually build their layouts over this paper diagram, while others remove each piece of paper as they go.