Determine the thesis of your essay. Specify what you will be describing in your essay in one sentence in your notes.
Write down the background context for your essay in your notes. Include any information that the reader needs to know in order to understand the main idea. This could include information about the historical, geographical or psychological context. Write down adjectives or descriptive phrases that you could use to frame the background context in a way that vividly shows the reader what you are talking about. As an example, if you are providing the general context of being in Italy, you can describe the smells of different foods when walking on the rough cobble-stoned streets of an Italian city to give the reader an idea of what it would feel like to be there.
Create an introductory paragraph that moves from the general context to a very specific concept using the descriptive adjectives and phrases that you have already listed in your notes. As an example, an essay that describes a restaurant in Venice could start with some general facts about food in Italy, then progress to describing Venice cuisine framed in a larger Italian context and end with a reference to the specific restaurant in Venice that will be described in the body of the essay.
Review your writing to determine whether it would engage your target audience. Include descriptive adjectives, similes or metaphors to set the tone for a descriptive essay that appeals vividly to the reader's five senses and sets the dominant tone and theme for the entire essay. Rewrite it to make it more engaging if you find that it does not pull you in.