Choose the activity first
Decide whether you want to watch a train circulate, practise shunting or make a detailed stationary scene. These choices lead to different track plans. A continuous circuit needs room for the manufacturer’s minimum curve radius plus margins. A short shunting scene needs useful siding lengths and an accessible way to operate points. A display scene may not need a power supply at all. Write one sentence describing the intended experience before shopping.
Measure the usable space
Measure the board and the access around it. Allow for doors, storage and reaching a derailed vehicle at the back. Draw the space on paper before laying out curves. The model-gauge calculator on this site converts prototype dimensions; it does not calculate safe electrical loads, suitable curve radii or whether a particular locomotive will run on your chosen track. Those details must come from component documentation.
Buy a compatible first system
Check scale, track gauge, controller type and the locomotive’s requirements together. A matching scale label alone does not guarantee compatibility. Read the manufacturer’s instructions for analogue or digital operation, power supply and permitted combinations. Beginners often benefit from a clearly specified starter system. Do not connect an improvised supply or mix electrical equipment because the plugs appear to fit. Keep tools, small parts and adhesives appropriate to the users and follow their instructions.
Leave scenery until the track works
Test the basic track arrangement before fixing it permanently or adding ballast. Make sure joints are aligned, vehicles can negotiate the intended curves and you can reach points for maintenance. Keep an issue list: a recurring derailment at one place is a reason to inspect that section, not immediately buy another locomotive. Build scenery in removable sections where access matters. A modest, dependable layout is more satisfying than an ambitious board that spends its time waiting for repairs.