Satisfactory

I always built temporary tracks at the edge for where I want things to match up. Remember you can always remove items when your done building an intersection.

The tightest reliable 90 degree curve you can make is a radius of 3.5 full foundations. So count from the edge one two three blocks, then halfway through that one is the closest you can make a reliable curve.

You can get tighter, but it won't be uniform, you'll need to manually put down the curve and then probably have another manually placed one.

For intersection blue prints I suggest don't put the blueprint of the intersection, but rather the temporary endpoints that you will connect to. That way you can easily lay down the endpoints you want to have, clicks few buttons to match the tracks up, then blueprint remove the endpoints. (Blueprints notoriously have some stitching issues with trains anyway, so I'd argue it's better to only use them for temporary train things)

I have spent WAY too much time building my rail network so please don't hesitate to ask. I think my last build we topped out at around 200 ten car trains running around at any given time.

In addition to the other tips here, I recommend having a two level rail system with one direction heading on one level and the opposite direction on a level above.

The pro is this way you don't have to worry about making intersections that cross over your main rail lines.

The con is that you have to build enough space to ramp up your track connections on level 2 but that's mitigated by just having around 2 train lengths of space length of space from the main rail before the train station

So it looks like this from the side

==========> Rails

---------------------- One meter foundation

At least 8 meters of space

<=========== Rails

----------------------- One meter foundation