Start with a subject that you should know well -- yourself. Begin writing a journal describing your roles in life and your specific personality traits. You want readers to feel they know you even if they've never met you. Recall a memorable event. Describe it in detail, including your reactions to the event, in a way that helps readers understand exactly what that experience was like for you.
Ask yourself what your motivation is when writing an article. If your objective is to move readers, connect with them by describing your emotions or other people's emotional reactions. If your goal is to describe the beauty of a certain vacation spot so that readers will want to visit it, describe what makes it unique and compelling to see in person. Your motivation should help provide direction for your descriptions.
Choose an image that strikes you as interesting. Write about the image or the scene. Circle parts of speech such as nouns, adjectives and adverbs. Using a thesaurus, replace the circled words with as many other similar words as you can. Rewrite your article using the new words. This exercise will help you to expand your vocabulary and to use more descriptive words.
Observe a sensory object such as a multi-colored soft scarf, leftovers from the refrigerator, or an interesting paperweight. Write down as many adjectives as you can think of that describe the item in terms of your five senses -- smell, touch, taste, sight and sound. Pretend that your task is to describe the object to someone who's blindfolded or actually have an assistant who's blindfolded try to guess the object's identity using your descriptive words.