Read lots of very good essays. A good place to find these essays is in “Best American Essays.” A new edition is published each year. I seldom buy the latest edition because they tend to be expensive. I wait until a past year’s edition is down to one cent plus postage in amazon.com.
Op ed (Opposite the editorial) pages in newspapers are a good place to find some great short essays. I like to read articles by Leonard Pitts jr. and David Brooks. Pitts won the Pulitzer for his op ed articles. I was assigning him to my writing classes before he won the Pulitzer for commentary in 2004.
These writers often use personal experiences in their columns.
Think about things that have happened to you and what they mean. How are these universal themes? We have all lost good friends and pets. We’ve suffered unfairness. Write about an incident in your life that changed you in some way. What challenges have you faced?
Practice writing essays in a notebook or a journal. Keep practicing. Know the importance of revision. Reread and rework your essays until they are as good as you can make them.