One of the basic skills necessary for cooking broths and stocks is being able to make a mirepoix. A mirepoix is very simple. It is sauteéd onions, carrots, and celery. Add some salt, pepper, and water, and you have a basic vegetable stock. Add toasted beef bones or chicken wing tips or fish bones, and you get beef stock, chicken stock, or fish stock, respectively. I used to hate celery as a kid, but I find that the celery really makes the whole deal. I add extra celery. I use white onions in my mirepoix, and mature carrots rather than baby (baby carrots have too much sugar, I think.)