Here are some things to consider in an ESL school:
Class size: Enough classmates for healthy interaction and practice, but not so many that the teacher doesn’t notice me.
Levels offered: The more levels offered, the more I can be sure that the instruction is the correct difficulty and pace for my needs.
Class structure: Are several levels mixed in one class? Is the instruction self-led (I listen to a tape or work on my own in a book) or are there lessons and activities led by a teacher?
Variety of students: Are all the students from one or two first languages? The more diversity, the more I will be encouraged to use English as the one language everyone understands.
Teacher qualifications: Do the instructors have educational background in Education, Linguistics, and English? How many years of classroom experience do they have? Do they do ongoing professional development?
Flexibility of instruction: Do I have any options to tailor instruction or courses to my interests and needs?
Atmosphere: Is this a place where I feel safe and happy? If I am relaxed, I will learn better.
Hours of instruction: Are there enough hours of instruction each week for me to make progress? Does the class schedule fit well with my life?
Price: Does the price fit my budget? Are there scholarships or financial aid available?
Outcomes: What is their student success rate? How do they define success?