There are great, easy-to-use, free image processing utilities you can use online. At Sporkforge I like the Comic Drawing Generator. Just upload a jpg image like this one.
Then Abracadabra Shazzam.
That was a Sensitivity Threshold value of 80, a brightness value of 200, the line option set to thin, and I checked "Apply Color" even though the image was black and white. Click the draw command and wait for the results. Then right-click the new image and save it to your computer.
By the way, this is a 1911 image of a cat on the shoulder of aviator John B Moisant from the Library of Congress Prints and Photographs collection.
Here's another image, a photograph of Siberian irises.
That was a Sensitivity Threshold value of 35, a brightness value of 200, the line option set to thin, and I did not check "Apply Color" even though the image was color to begin with.
Understandably, there are limits on the size of images you can upload to Sporkforge, and what you can do with them there. But it's a fun way to get started.
There are other online utilities that give you more options and are just as easy to use to explore another day. And I'm working on Gimp, which may have a steeper learning curve but when I get over the hump, watch out!