first thing i like to do, when i care, is get longer motherboard standoffs, and insulate the motherboard power wiring, and at least 1 set of drive wires, and lay them UNDER the motherboard.
that takes care of 1/3 of the mess.
fuck floppy cables, they're never the right size, but if you want to make life easy, you can make your own "rounded" IDE cables out of standard ones, with a section of heat shrink tubing and a couple of zip ties.
not great, but much better than without it.
you can hide alot of the excess wiring (like the small goofy connector that every power supply has, but i have ZERO idea what it goes to) on the opposite side of the power supply (on the back side of the case, viewing from the window)
there are a ton of things you can do to make it your own style.