Apply to a University that offers an ESL course, such as Rice University in Houston. Read the requirements carefully before applying, and make sure you have all applicable education requirements.
Volunteer with Literacy Advance of Houston. Volunteers teach adults to read and write English. This organization also has an ESL program, as well as Adult Basic Education and Family Literacy. There are also classes available for those on a waiting list.
Work at an ESL center, like the one at the University of St. Thomas in Houston. The center offers several programs for students, ranging from academic purposes to executive experience.
Create an advertisement and post it online or in a local newspaper. Set your rates and stick to them, and make your advertisement as complete as possible. State your credentials and previous teaching experience, and make sure you post a contact number or email address.
Apply for a high school English teaching position. Check with your local school board, or through a private school listing for available positions. Search known job boards in your city for appropriate job listings applicable to your education.