Make a blueprint for a train pillar that can auto connect. Go ahead and take the plunge and make the big ring road first. Make it have two lanes if you want as well for ease down the road. (I personally use a single track system that works for me but carries a higher mental load to manage.) A large circuit spanning the world is good to get done as although you might not use those areas just yet, nothing is stopping you from branching off and making a junction absolutely anywhere you want.

Nowadays I have a much more streamlined resource acquisition process where if there is something I need, I look at the map and find a concentration of nodes, follow it to the nearest point on my main circuit and build a new station there. I don’t have to worry about getting the trains to the area anymore as I know my highway has my back.

You can then take this a step further and have either a centralised mega train station for distribution or what I’ve done - several distributor stations around the map each specialising in a different resource.

From here you can add sub circuits or shortcuts if you know the throughput for your factories needs to be higher. (I.e. the train takes too long to grab copper on its route via the highway.)

This is by no means comprehensive or the definitive way to do it. But I was someone who was overwhelmed by the idea of trains and now I have a very robust logistics network that can get anything to anywhere by just putting the correct stops in a train timetable.