A good photograph, map, or other graphic in an article can help clarify things. If you want one but are stumped, or totally lost about copyright rules, one really good way to find graphics is to type "public domain" into the Google image search window, along with an appropriate key word. An extra benefit is that you have a high probability of finding photographs that are legal under the Wikipedia rules. (Remember to copy down the artist's name and URL for recent photographs labeled "public domain", because you will need the information when you upload the graphic.)

Of course, you shouldn't forget to look on the Wikimedia Commons first‍—‌someone may already have done the hard work! (You can use images from the Commons in the same way as local Wikipedia ones.) Here is the link to Wikimedia Commons search.