Brainstorm a list of possible setting elements. You can draw from memory or from pictures you've seen. Though you may jot down many things, you probably will not use all of them. Chances are, your essay will feature a person or character; include items that help the reader to understand that character. For example, maybe you plan to write a narrative essay about your 30-year-old sister, and you know that she still keeps stuffed animals on her bed. Including the stuffed animals will not only enrich the description of a particular setting, but help the reader to know your character.
Show, don't tell. When you try to describe with comments such as "it was a lovely day," you are telling readers what to think rather than showing them what a setting looks like. Ask yourself what things populate the setting, like flowers, green grass and singing birds. Include the ones that resonate with meaning. Choose and include physical details from among their sizes, colors, textures and shadows.
Avoid adjectives such as "beautiful," "dreary," "ugly" and "pretty." Replace them with sensory impressions that include visual imagery, and when appropriate, sounds, tactile impressions, tastes and scents. Mention the quality of light, which helps to establish mood.
Weave elements of setting into the text. Where a paragraph of landscape description might work well, a page of nothing but landscape description is probably too much. It will read like a catalog rather than description. Instead, include a paragraph to establish the basics, and then work in more particulars as you write.