Work slowly and pick an area that's not too big to start. Come up with a route plan and stick with the theme all the way through.
Contrary to Cascade Railroads's approach, I will finish up small sections at a time, maybe 4 to 6 baseboards a day, building them up with details and moving on down the line. I found using that method, I can move pretty quickly without burning out. If this is a DEM based route that has been base-textured with a topographic map, I will lay all my track on that first and work down the line leveling, landscaping, detailing, etc.
Invisible stations are okay and be very helpful. I find the VSR stations by blodknok (James Moody) to be excellent. These are just platforms without buildings, and are high platforms to begin with. The issue with them is the double track stations are UK track space which is about 4 meters and not 4.5 or 5 meters as in the US. For where I need double-tracks stations, I will use to single-track ones instead and space them accordingly. There are also some wooden low platform stations available as well if you are interested in putting in some of those. Offhand, I can't remember the builder though.
All and all, it's up to you how you do this, but I do recommend going about it slowly.
John