I’d also strongly suggest nabbing yourself some cable ties or thin Velcro straps, which will come in very useful for cable management.
There are a few optional bits as well: you may need a Wi-Fi card, USB dongle, or powerline adapter kit to connect to the Internet, should your chosen motherboard lack onboard Wi-Fi or you can't use an Ethernet cable. I’d also strongly suggest nabbing yourself some cable ties or thin Velcro straps, which will come in very useful for cable management. Also, you'll need a working PC or laptop if you're creating USB installation media yourself; you won't if you're buying a ready-made Windows USB from Microsoft.