Firstly with any idea, especially one that you know is going to end up over complicated, best to do a few drawings 1st just to make sure it'll work, or close! :)

Step 1: Supplies.

Ok, now you think it'll work, better start thinking what supplies you'll need? In my case, trying to make my VW T4 Van 'GLOW' is going to require someone (ME!) to make a custom wiring loom! :/

Step 2:

Ok, time to start actually building things, planning often changes while you're building, there is always the unforeseen stuff to contend with! ;(

Step 3: Bench Testing.

Right, before you fully assemble your project, bench test as much as you can, nothing more annoying than getting it all fitted together & it not working, then having to disassemble it for something stupid! :(