If your going down the foam route I'd recommend Armorsmith as your paper patterning tool, having a digital mannequin is so helpful. Apart from that I'd just say read everything you can on different builds, don't just read up on FUD builds, check out stuff like Ironman armour builds along with other halo builds. I pick up so much more reading a Halo Reach build that I intend to bring into my Halo Infinite build.