I usually write something small that I've written multiple times before. I try to write it exactly like I would in whichever my currently most-used language is. It gets really painful in parts because languages differ. Sometimes the writing is the difficult part. Sometimes writing it in the same way is easy but the runtime performance is bad. Sometimes the tooling just doesn't support what I am trying. Finding these pain points helps me develop an intuitive sense for which of my habits I should steer clear of with the new language. After I consider how the new language would allow or encourage me to write it differently, I re-write it. Then I diff my original and final implementations.