Tutoring is my main school year side gig. If you're looking to get into it, I would try stopping in to the local high schools and universities in your area to see if you could post any ads for tutoring or possibly get onto a tutor list that the schools would provide to students or families looking for a tutor. Try marketing specifically which courses you would tutor, that specificity really helps bring in more people.
I started working with a service called Tutor Doctor, but I found that Tutor Doctor paid me too little for my time, and it was also a huge drag having that money show up on my year-end taxes. If you're having a hard time finding anyone to tutor, it is an option, just know that they always take a good chunk of the cut and they let Uncle Sam in on the equation. With a Masters degree, Tutor Doctor paid about $20 less per hour than I was getting working with students privately, so I slowly phased out working with them as I found more students being on my school district tutor list.