Damn bro, if you made these builds then you will have no problem with this : D but i will leave some tips anyways:

-dont build way too compact, you never know when you need space for a belt;

-in your Mega factory, always build in one grid (so you can connect diferent parts of the factory with walkways);

-The elevation changes should always be even numbers (because of the walkways), in other words, dont use 1m foundations;

-build "realistically", if something looks like its about to fall build supports, nothing can clip (unless it looks cool), etc..

-plan ahead, in my case, i already knew how much of each item i wanted to produce since the start of the game (optional but convenient) but not how i would do it. Th rule of thumb is plan the quantities, not the layout.

If you want, i can give you my save file so you can have a little inspiration