WikiHOW and About Education are both websites that provide several easy-to-follow examples of good descriptive paragraphs written both by professional writers and by students. Each site also provides tips and instructions for writing descriptive paragraphs.
Good descriptive paragraphs can be written about either people, feelings or things. Try to choose a subject that is familiar and significant. Focus on details that engage as many of the reader's senses as possible, not just sight or even sound. Try to view the subject from a fresh angle, and proceed with the description in the order of features that this view presents to the observer.