Here’s an example of one of my illustrations done of historic uniforms. In this case, it was a Japanese tank commander from WWII. I started off by gathering plenty of uniform reference photos. Most people, when pressed for time will grab the first bit of reference off of Google Images. Sometimes it’s better if you look deeper, so as to avoid historical errors or an overuse of stock images. I like to check auction sits such as Bonham’s or Christie’s. EBay is a pretty good source too!