Lower class clothing can be an absolute pain to research - for starters, there are comparatively few manuscript illustrations depicting the lower classes, particularly the more impoverished members of the merchant classes, tradespeople and peasants.
Often, it's tempting to make lower class clothing based on contemporaneous upper class clothing - by either subtracting the most expensive aspects, or simplifying things. Another idea is to assume that, due to the second hand clothing trade and a (supposed) trickle-down of fashion, lower class clothing might mimic clothing of wealthier individuals of a decade or a few decades earlier. However, both of these methods are based on potentially flawed assumptions.
So, what can one do?
Luckily, there is a wonderful resource that can help you find original manuscript images of lower class (and upper class) clothing, as well as give you a better idea of how fashion for both poor and rich progressed from the 13th-16th Centuries: The Roman de la Rose Digital Library.
So, without further ado, a tutorial for getting the most out of this resource: