There are already dozens of tutorials to setup an Arch and Windows dual boot - welcome to a dozen + 1. Like most others this is a step by step guide. Unlike most others the steps are ordered in a way that makes sense (starting with the download first - duh!) so you won't have to restart your computer a gazillion times.
I did this on a single SSD Dell XPS 15 with windows 10 preinstalled. It's obviously possible to follow this guide if you're installing Arch onto a different drive or if you're running older hardware. If you run into any problems please be sure to read through the Arch Installation Guide and the Arch Dual boot with Windows wiki.
To get started you will need:
- a stable internet connection
- a USB key with 1GB storage
- a cup of coffee & and a can do attitude