The very best and most realistic model railroads layouts are those that grow almost organically! By that I mean every little tweak and adjustment will make a small difference and if there are say, twenty tweaks there will be a big difference.
Therefore organic growth is almost inevitable because I'll lay odds that every time a modeller goes to his favourite stockist he will buy something to add to the layout.
So building a really complex layout can almost be addictive.
If the layout is the product of human imagination it will be the subject of seething change for no lees a reason that every time we read a book, see a picture or another track we see a change or enhancement for our own layout.
Size and space is the only limiting factor.
Not forgetting that money is always a consideration.
It is the scenery that really brings the layout alive.
Just having model trains and rolling stock going round is only interesting on a technical level and easily forgotten.
Scenery gives the layout atmosphere and so do other accessories such as people, buildings, roads and signage.
It is inevitable that at some stage you will need some form of control center if you have more than one train and points that are remote controlled.
We shan't go into the exact detail here but you can find detail enough on my website.
Starting from a very simple oval layout you are able to build an extremely complex layout with standard components from your hobby shop, for instance you can introduce un-couplers to the sidings and detach rolling stock using a control box placed near your transformer.
Un-couplers can either be attached to the straight or curved track using two trains.
If switching operations appeals to you, why don't you buy more switches, two curved sections of track, and two half-length straight sections.
Then you'll be able to make a primary turnout from the main track itself, as well as a secondary turn out coming out of the first one creating sidings.
The length of sidings is determined by the space available, but so long as they hold a freight car or two, which can complicate things.
And let's face it, "complications" are exactly what makes this hobby so interesting.
One of the best ways to utilise space is to build inner and outer tracks and connect them with turnouts (points).
Again it makes for interesting switching because now you will have to be careful not to crash your locomotives into one another.
Let us imagine your layout is currently set out as tow ovals, one inside the other and connected with three turnouts and three lines of sidings.
You have 4 Locomotives and ample rolling stock.
You know all that scenery you have been buying? Now is the time to start putting it into place because your layout is big enough for some essential atmosphere.
I doesn't mean that you stop improving your layout but it does make future planning easier because now you have defined space.
It would be easy to detail layouts in the same way as manufacturers do but I promise you that a layout that comes for your imagination will be much more satisfying than just buying your stuff from a list.
You will be forced to talk to your hobby shop staff and other modellers for ideas and this is a far more satisfying way to build your layout.