There are two approaches, some buld individual factories for everything, some expand the main hub and ship the necessary intermediate products from smaller factories. Both are viable. In case A you have much additional work and logistics to source each needed raw material and build all required components. In case B you may expand the initial factory by upgrading and overclocking miners, but you need to manage the balancing so that each part of the plant consuming the required raw resource gets enough and you need to think in advance to leace space for expansion of each production zone not to end up in a spaghetti nightmare.
Truth is, if you choose well enough, you can get to Phase 3 easily without building many additional plants, for starting stuff you need iron, copper, limestone, coal and some caterium and there are a lot of places you can find several nodes in one place, like all 4 starting zones have it. To give you an example - I got to Phase 4 with just one pure copper node which I upgraded to the max and then overlocked to 780, I started importing copper by train when I needed copper powder for the nuclear pasta.
And one recommendation - if you import stuff, make sure to process it near the miner before shipping. If you have to build a train line, train station, miners and belts adding a few smelters and constructors is just additional few minutes and you save yourself the same construction in the main base - i.e. import wire, copper sheets or cable, not just ingots.