When looking for an instructor you need to know 3 things.
Your budget for lessons is number 1. At my facility we have instructors charging from $100-175 per hour with discounts for purchases of series of 3 hours or more. You may be looking for group instruction which is much cheaper.
Second on the list is look into the experience of the instructor. Go out on the internet and look at their bio, and even some reviews.
The third thing is to go and meet the instructor and if possible hit balls near by them and listen to a lesson or two. You want someone who gets to the root of the problem and isn’t stuck to a method. If you play golf and want to get better, you may not be prepared for a full make over, and a lot of instructors don’t know any other way.