1. Location matters.
If the school is too far away from home, work or school, you'll have more time to think of a reason to skip class. Closeness counts.
2. Visit at least three schools.
Don't join the first school you visit, no matter how compelling you find it. If you become a faithful adherent to martial arts, you could spend years studying and paying dues. That's a huge obligation and I believe a worthwhile one. However, your mind will never be more impartial than when you begin. Compare schools and you're more likely to make the right decision. Visiting a school helps as a reality check against the glamorized movie version of martial arts.
I suggest you should try at least two or three different martial arts. I hold rank in karate, jiu-jitsu and judo and I've studied a bit of wrestling. On the other hand, I've never had a boxing, Muay Thai or Sambo class. You're either a striker (someone who favors punches and kicks) or a grappler (grabbing hold of someone). You might not even know intrinsically which you prefer until you try. I'm a natural striker (punches and kicks), yet I won a jiu-jitsu world championship (grappling). Sometimes you just get lucky.
4. Listen well.
Talk to the instructor and listen carefully. Sometimes a certain chemistry occurs (or doesn't), and you know it's a fit. If the instructor doesn't exude some enthusiasm when talking about his art, that should raise some concern.
5. Sign here.
Sign up for the shortest time possible. I believe martial arts instructors should make a reasonable, well-compensated living. I also believe it's an unwise financial move for a novice to enroll for an extensive commitment and then realize the interest was a passing personal fad. Sign up for the introductory offer if they have one, and when you are confident of a commitment, a longer term is acceptable. Pay your instructors on time.
6. Watch a class.
Most importantly, watch a class that you would attend. If you're a spectator at an advanced class, you're not likely to witness the pace, instructional style and nature of the instruction that you will receive. An advanced class can be a motivator, but the novice class is where you will begin. Remember, every black belt started as a white belt. In some schools, the instructor combines all ranks into a single class.
7. Special categories.
This applies to children and some women. Talk to the parents of the kids at the class you're observing to develop a sense of why your child should attend. The essential standard is whether your child seems to enjoy the lessons. Some women prefer classes that have only female attendees. If that's your preference, look for a school with that class type. A word of caution: If self-defense is an essential factor in your search for a school, a potential attacker will most likely be male. Practicing only with other women only tends to ignore this obvious consideration.
Almost all martial arts have a sport and a self-defense component (isn't that why they started?) But, oddly enough, some don't have a class that shows how your techniques actually apply to a self-defense situation. Ask about self-defense applications and whether they have a class addressing this issue.
9. Physical limitations.
If you have any physical limitations, raise the issue with the instructor. If you've had a neck injury, for example, practicing chokes might not be a good idea. It's also wise to check with a doctor. Martial arts are a contact sport, after all.
This is probably the most crucial criterion for choosing a martial arts school. How does it feel? How do people treat each other? What is their attitude and conduct toward the instructor, and what is the instructor's attitude toward the students? If you don't feel comfortable with the school's culture, you won't stay.
For a detailed explanation of choosing a martial arts school and answers to every question a beginner might have, visit https://amzn.to/3xwkPKH