I have traditionally recruited students through a few methods: contacting and getting to know the local public school teachers, being active in the community as a performer, adjudicator and educator, and through word-of-mouth through other colleagues. In the past year, I've also created a website and added myself to several free "private teacher search" websites. While the free websites that advertise teachers increase the web presence (and suddenly make people think I must be better than I was when my name didn't pop up so much in Google searches - LOL), I haven't received any referrals through those services.
Right now, I have 20 students, ranging in age from 10 to sixty-something. The majority of my current students are in elementary through high school.
As far as age preference - I really love having students of all ages and skill levels. It makes teaching rather fun, to see the eyes of an 11 year old light up when they play their first G major scale, to see the excitement when a high schooler sees the correlation between a skill they just learned in a Barret etude and in solo literature, the joy of seeing a young person accepted as a college music major, and to see the sense of true amazement when an adult who hasn't played the oboe in 20 years gets up and plays a solo in front of their church. I like variety. Though, I must admit that there are some ages that can take a lot of extra skills and energy to teach (for example - 13-14 year old boys with a short attention span!)
I have had successful studio recitals in the past, but in the past several years, the scheduling for both students and my busy schedule has made it difficult. I think recitals are very helpful for students, but it's important to realize that some students are truly terrified by the idea of performing by themselves in public. I try to encourage students to do so, and those who are really nervous will play a duet with me or a trio with other students. I think the recital experience (or "Solo and Ensemble Festival", which is a state sponsored event I basically require my students to attend) is important for a person to experience. It helps them learn how to deal with nerves, how to plan their work and prepare well, how to keep composed under pressure, and how to deal with and learn from both success and disappointments.
Lesson materials for me are based on method books appropriate for the student, supplemented with warmup routines, solo literature and technical exercises. I cover "band music"/"orchestra music" on an as-needed basis - in other words, I don't give weekly lessons that are just supervised practice sessions for band class. For beginners, I work a lot with their beginning band method, supplemented with a warmup routine and an oboe method bood (Gekeler 1), plus quizzes and exercises I've developed to build additional skills in note reading and fingerings. Slowly, I get them more into the etude & solo literature as they gain more skills and can play the band method music without help. But, if they have a test, a quiz, or have difficulty with their school assignments, they are always welcome to bring that music to their lessons.
Do your students seem to end up in a similar range of abilities or is there a wide range? That's a good question. I would say most of my students end up with significantly above-average skill levels, however there always students who don't practice very much (or hardly at all). My goal is to push them to make practice a regular part of their homework schedule, but some don't respond to this. I figure that their lessons equip them to be better players than they would be without lessons, and I focus on helping them develop good problem solving skills and time management, drawing parallels to how these lessons apply to other things in life outside of playing the oboe.
You mentioned that your studio is growing significantly. You might want to consider using a service like "MusicTeachersHelper.com", which I started using a little over a year ago. It keeps all of your lesson schedules online, emails students (and parents) reminders for scheduled or cancelled lessons, emails them their assignments for the week, sends automatic invoices for payment, and you can broadcast messages (like studio events, concerts, track loaned items, etcetera). I've found this system to be incredibly helpful in managing a lot of the paperwork for my studio, people pay on time for their lessons, and fewer lessons are missed. Kids love the online system.
My understanding is that there are a few of these types of systems available. I've just used MTH for over a year, but I never tried the others.
I'd also strongly recommend developing good lesson policies on what you expect from students, as well as a clearcut cancellation policy. I also have those stored in my music teacher's helper system. This has helped quite a bit. If you want to see what I have out there, visit https://oboe.musicteachershelper.com/studiohome
By the way, I am in no way affiliated with those who own music teacher's helper (i.e. I'm not making any type of money for endorsing it). I just think it's a good system that has streamlined my paperwork and communication with families, and it's worth the tiny monthly fee to use.
I hope this helps a bit!
Good luck with your growing studio,
Lynne Marie Flegg