I wrote an article a little ways back where I give my perspective on how to find a good BJJ gym to train at for people who don't have any experience. Since I get a ton of questions through PMs here at P-F for the same thing, I thought I would post it here. Hopefully, at least a few folks may find it helpful.
http://www.iacombatives.com/2017/12/...-a-bjj-school/
here is a short excerpt on what I look at when i step foot in a new gym:
"When you go to look, watch the makeup of the class. Unless it is a specific class (like a competition class, or a MMA training night) than ideally the class should be composed of all types of people – men, women, younger, older, etc. A class made up of young, athletic dudes is probably not the environment you want as a beginner. A class with all types represented tells you that the gym is open and welcoming to everyone and has no issues accommodating different people.
Pay attention to the “vibe” of the class. Do the students communicate freely with each other and the instructor, or is it a rigid, military type environment? While discipline is a requirement, it can be taken too far in martial arts. I want to see the students laugh and joke with each other. Yes, be focused and serious in their training, but there should be an obvious element of fun present. The same goes for the interaction with the instructor. He should be able to control the group without resorting to being a drill instructor. An instructor that jokes and smiles with students means he does not see himself as too elite and above the group."