My aunt makes a much more complicated version of this soup (and she won't give me the recipe!), and this is the best recipe I can find in its place. There is a LOT of room for variation, so have fun experimenting! This is the original recipe here.
The easiest way to make the meatballs is to roll them into a 3/4 inch "log" and then cut them off in 3/4 inch segments, THEN roll them into meatballs. My sister prefers to brown the meatballs first, but I like them better this way. Also, it is best to add a small portion of meatballs at a time. When the meatballs cook they rise. Once they begin to rise, add more meatballs and stir gently.
I also add a clove of garlic to the meatballs and I usually double the breadcrumbs.