I'm not an instructor, I'd like to own a gym one day and possibly include jiu jitsu in there, but I'll point out a couple things I've learned, and you can see if it's helpful at all:
1) You have to develop a way to transition people into Jiu Jitsu. You're not always going to have readily-dedicated people coming in who will just persist from Day 1, so you need to know how to help the person who may just be curious, or just looking to train as a hobby, to get involved in your school. I can't remember who it was, but a pretty prominent MMA instructor said in an interview once that while his passion is working with and training pros, it's the kids and weekend warriors that help keep his doors open. This might look like offering 2 complementary classes, and then having a discussion about what is expected if they want to continue. This is the reason, I think, that a place like CrossFit has their on-ramp programs, so people can gradually get into training, instead of just jumping in the deep end.
2) You have to be passionate about your school, and training in general. If you look like you're not all that thrilled about being there, and maybe only really want to improve yourself, it's going to trickle down to your students. Students, current and prospective, need to feel that you give a shit about them and their development.
3) You have to develop ways to keep students accountable. Accountable for showing up to class consistently, paying their dues consistently, keeping their teammates accountable for training consistently, or at least accountable for communicating why they aren't doing these things. Obviously things come up in life and sometimes people have to step away for a bit, but you can't complain that students aren't training consistently if you don't develop that culture in your school.
4) If you want to train kids, and get the money that comes from having kids' classes, then you also need to foster a family friendly environment. That might mean having rules about the kind of language that's allowed, or if music is allowed and what kind, etc. Students who are parents are more likely to be able to see their school as their kids' school if they feel it's a safe environment for all people.
5) Regularly acknowledge your students' improvement, or provide constructive criticism of mistakes. People just like knowing where they stand.
6) Keep your space clean and in order, and be consistent and punctual as much as possible. Respect what's your's, and what is your students', including property and time.
Anyway, these are just things I've noticed in my years training around different academies and talking to friends who train at other schools/gyms. I've noticed pretty consistently that the people who's gyms/school aren't as successful as they'd like, aren't doing these things and doing them consistently. Good luck.