What is the subject of the observation? Does the paper clearly identify this?
Add a sentence or revise your opening paragraph so it clearly identifies your subject.
What is the viewpoint of the observer? Where is the observer in relation to the subject?
Pretend you are a photographer looking at your subject. You can't shoot every angle. Choose a particular way to view your subject, and write from that viewpoint.
Example:
You can't describe a whole basketball game easily, but you could describe one particularly fantastic player.
What objective details do you use to recreate the scene?
Add facts about location, sequence, size, or whatever else might be relevant to recreate your subject for your readers.
What descriptive language have you used to make your subject come alive for your readers?
Add specific language that clearly expresses what you've observed. Try replacing vague words with precise nouns, verbs, adjectives, and adverbs. For example, instead of saying, "The kitchen was filled with smells," say something more specific like, "The sunny, yellow kitchen smelled of grandmother's hot, baking apples and cinnamon."
How did you organize the details to help the reader make sense of the description?
Choose a method of organizing your paper that moves the reader through your observations using some sort of order. Chronological order works well if what you're observing happened over a time period. Order of importance works well if you're trying to recreate for your reader the lasting impression that certain aspects of your subject made on you.
What conclusion about your subject do you want your reader to reach after reading the paper?
Restate your main idea. Make sure the details you used to describe your subject lead the reader to the conclusion. For example, if your goal was to have your readers decide that visiting a big city was fun, you might not want to include details that would suggest the city is a dangerous place.