When making these kinds of soups, think about the strength and subtlety of each vegetable to decide how much to put in the soup.
If you just throw these vegetables in a pot of boiling water with a bit of salt and purée them, it's going to taste decent. If you start adding different levels of seasoning or stocks, it just gets better and better.
You can add croutons, a touch of cream, or chives to the soup.