Factorio

After making my starter base, I was working on a train system using train limits, circuits, and bidirectional 3-8-3 trains. I realized the scale was too large for me, and I wanted something smaller and simpler. I had also messed up the fueling system, and wanted to redesign it.

I nuked the old system (literally and figuratively), and I want to switch to unidirectional 1-4 trains, but still using train limits and circuits to calculate the limits. I also want a single fueling (maybe adding multiple as the factory grows) station that is visited by all trains.

Any suggestions for planning or designing something like this? The only mega base I have ever made was a spaghetti mess and I'm trying to be a bit more organized in the creation of this one (the initial goal is 2.7k spm)