When you're working with CSS documents, it's often easier to think "globally" about your document. By this I mean, think about how the majority of the elements are styled and define that style first. Then, you can go through and fix the exceptions.
For example, if your document text is going to be primarily arial, geneva, helvetica, sans-serif, you can set a rule for all paragraph tags at the top of your stylesheet:
p { font-face: arial, geneva, helvetica, sans-serif; }
Any paragraphs that are an exception can be defined by class or id rules:
p.pullquote { font-face: times, new york, serif; }
