I've got an O16.5/On30 garden railway in the pre-planning stage and I would be grateful of any advice.

It going to be mostly British outline with some American rollingstock

4760885 with track lay it onto a firm level surface prefrebaly concrete placed on chicken wire then blend it into the ground with brown ballast and don't rely on fishplates for conductivity solder dropper wires between each rail joint. The same goes for buildings. I recommend useing white metal detail parts as they will withstand the British weather make sure the track bed is well drained too invest in a good track rubber or Dapols mobile cleaning wagon.

4760885 Rule 1: Don't get over ambitious. Building a garden railway is just like building a real one, only smaller. There's a really nice youtube series detailing the building process from start to finish Here

4760904 will do, i was going the solder the joints in the track, so it's essentially continuous welded rail, though i will be having small gaps where the fishplates are, so it gives a "click-clack" of wheels rolling over the track

4760917 If it goes according to plan then my railway will be a simple-but-large L-loop, at different points there will be a yard exclusively for freight wagons, a main station serving a fairy town, an engine shed (this will be at the end nearest the house with the running line going behind it) with a hand operated turntable and a second yard for coaches. there will also be small halts at different points.

this means that the main attraction is the single running line, but there are different points that add operational interest.

Radio controlled battery power is the best system I've operated, but I can't afford it. If you are planning on it being really permanent you can have bus wires that feed every other section of track. If you go with battery power laying track is a breeze, one of the reasons why I model in 7.5" gauge is I don't need to worry about cleaning track and soldering rail joints.