Now that you've laid out the essentials, what do you really want? Take that basic theme you've already created and build upon it.
Making a List
Start with a list of all the things you want on your layout. Separate columns for "Must Have / Would Like / I'll Take It if I Can Get It" help keep things in perspective.
Your list should include things like scenic features, operating schemes, control systems, benchwork designs, and any other special desires. "Must be child friendly," "Lots of bridges," "Plenty of switching," are all worthy goals.
Maybe you already have a favorite prototype. If so, take a look at your list and see what part of that railroad best suits your needs. A popular line like the Santa Fe for example could be used for a prototype for anything from a busy mountain mainline, to a seaside port switcher, to a flatlands racetrack.
Maybe you don't know exactly what railroad you want to model, but you know what you want your layout to look like, or how you want it to operate. Your list can help point you in the right direction.
Its also a good idea to include smaller goals in these early plans as well. "All curves should be super-elevated," might not have a major impact on your final trackplan. But keeping this goal in mind from the beginning will help ensure it gets done in the end.
Checking it Twice
It's good to get everything on the list to start. But once your list is complete, be prepared to start cutting it back. You probably won't have room for everything. Let the negotiations begin!
This may take some time. With so many options available, there may be multiple ways to get what you want. You may not be able to change the essential elements of your layout plan, but you can be very creative in how you work within your constraints. You will probably revisit your priority list frequently as you proceed with the design.
