The typical strat most people go for is called a "bus". Basically, its like having a central highway of commonly used materials, like iron, copper, and green circuits, that runs through your factory. Then you branch off the bus belts to have sections dedicated to different materials.
So, my highway might start with two belts, one of just iron plates and one of just copper plates. Later, I'll use splitters to split off some of those plates to the side to make green circuits (I'll make the copper wire there for just the circuits, too). The output of that will become another lane on the highway, since a ton of shit needs green circuits or green circuit byproduct. Steel is usually the fourth lane.
I don't make loops out of my belts, they just branch off and dead end wherever. Its not a problem at all if materials pile up at the ends, but also every belt holds one specific kind of item (so JUST iron plates). Sometimes I let two items on a single belt in its own side but that can be trouble. Some assembly machines might "starve" but that just means I need to expand, make more.
An assembly line might look like this:
||>O>|
||>O>|
||>O>|
||>O>|
Imagine the O's smelters, the west |'s belts of coal and iron ore, the east | a belt of iron, and the >'s the various long/yellow inserters. See how I can expand iron production by just repeating the pattern northward? I can also mirror the smelters westward. If some smelters lack fuel or ore, then I need more mining. If the ore is always saturated, then I need more smelting.