I recently went from zero to a pretty nice 9.5 ft x 5 ft layout in just a matter of a few weeks, in O gauge, with no layout plans. The table is built, the track is laid, the wiring is done, and two trains are running. The only thing I am doing now is installing eight different power attachments to the track, so that I can have eight separate power blocks, and I am in the process over the next two days of running all of those wires under my table to my currently open-topped control panel. When I get the two MTH power distribution strips I ordered a few days ago, and the fiber track pins, all of that will get done in a matter of hours. There are several separate routes that the trains can travel.
Now, for total honesty:
1. I have not yet put the cork underneath the tracks. I want all of the track fully screwed down, wired, and thoroughly tested for hours first, and then I will just unscrew a few sections at a time, lay the cork bed down, and screw them back on top.
2. I did not build any trainyard. I think they can be really beautiful in large layouts, but they take up large amounts of board space, use a large number of switches, and of course they assume that you like running your trains backwards. I don't. I use side tracks to park my trains, separately blocked with ingress and egress switches.
3. FINALLY, THE BIGGIE: At this point, my layout board is just painted in a flat green. I have not put in any landscaping. Personally, I think that there are really no shortcuts to creating really great and realistic scenery. I don't have the patience or talent for it, so I am just going to use some sprinkled grasses and soils from Woodland Scenics. I also have access to a small trainshop, that buys used stuff at shows, and they have lots of fully assembled O and HO gauge buildings from old layouts, custom painted, that look great, and cost about 1/2 of the price of a new kit for the building. So, I am going to pick out several, and put them down.
Do I have a scenically beautiful and fully realistic looking layout? No. But, I like watching my trains run. Little figurines, automobiles, and the tiny details that go with them just don't interest me that much, though I do appreciate the beauty of the layouts where people have spent 100s of hours properly incorporating these.
Don't know if this helps.