2 Let’s get kitbashing
I use my model as a first-base reference to build up the armour. I use 3ds Max, but any 3D package will be fine. You only need to move and rotate objects around. I’ll be starting with a pose, then dressing up the character in armour. A pose that’s established early on helps to give the subject a purpose, so you can then concentrate on the general look instead of practicalities. In my mind, the look of a design comes first, then I try to find a way to make it work, rather than the other way around.