Here’s some ideas from my experience:

• Use https://u6.satisfactorytools.com/production to help plan Production. You can pick which Alternate recipes to use, and work out what you can output, and from what Inputs you’ll need.
• Break things down into separate production pipelines, for more manageable chunks. Rather than build everything in one mega-factory, have smaller factories for grouped similar items, with similar raw requirements. Using the planner above, you can put Products from other factories as Input items.
• Use Trains to shift resources around. This could be moving raw ore from a remote mine, to moving mid-tier components like computers to another factory for higher-tier things. (Later on you can use Drones!)
• A more extreme way is to make mini-factory blueprints, and then just put down however many you need within a larger factory. You can make Heavy Modular Frames in one blueprint (using Iron Ingots, Steel Ingots and Concrete as inputs).
• Reusable blueprints can also simplify the tedium of larger builds. eg; a Blueprint with 8 Constructors at a time, or 6 Assemblers, that you can chain together.
• You don’t need mega-high throughput for many late-game items. Ignore the mega-factories popularly shown online.
• Try to keep expansion in mind when laying out a factory. Have a rough idea on being able to scale it to 2x or 4x throughput (eg; building extra floors of the same layout, or stretching a manifold out to double-length).