The Broth: If you are buying the vegetable/chicken broth for this recipe, try to find one without all the additives especially if you are MSG sensitive (a migraine trigger for many). The majority of commercial soup brands contain the flavour enhancer MSG but you wouldn't necessarily be aware of this without investigating the ingredient list -- monosodium glutamate. The good news is that most grocery stores carry at least one or more natural soup brands with low-sodium, MSG free broth (they will frequently label "MSG Free" directly on the front package).
Seasoning: You can season this soup any way you desire. It's perfectly fine on it's own but I also like to serve it with a splash of soy, balsamic and/or worcestershire sauce before topping it with coleslaw (shredded cabbage).
Heat: If you're in the mood for thermogenic heat, you can add some chopped chili peppers, chili powder/flakes, a pinch of cayenne or chipotle as desired. Smoked paprika would also make a delicious variation.
Adjusting Thickness: Depending on how thick you like your soup, you may wish to add more broth once the barley is cooked and you see what the consistency is. I love broth and find it comforting to sip on so I make little adjustments as I go along.