Hi, I'm a private tutor and I'd say that I prefer once a week to keep the momentum going but biweekly is acceptable, especially if the student is proactive and self powered, if the student is very dedicated, and the tutor gave enough direction and set work/reading to keep them going, even once a month could be ok but many tutors won't be up for that as it's hard to manage and they have to earn a living. For the best, but equivalently priced tutors Keystone is the best, followed by Holland park, owl tutors and then the websites, I also highly rate tutorhunt and first tutors, you can find the best tutors there too and it's much cheaper, there's also tutorfair, alpha, impact, tutorful and fleet, others too but these last lot are new comers onto the scene and are trying to uberise tuition which means devaluing the service for their own gain, good quality tutors who are actually good and value what they do either have to charge much more on those sites, as they take a cut from every lesson, or they attract inferior tutors. Also, I'd sincerely recommend not going with a graduate or someone inexperienced, they might know the knowledge and sound good but have no idea about the exams or exam board requirements let alone best teaching practice, I've had to clean up a lot of messes created by these types of tutors. I'd say look for a qualified teacher who is tutoring, not necessarily still teaching as right now the smart people realise mainstream school education is a little broken at the moment and have left to do an excellent job of tutoring and helping students on their own so that they can do what they love and not be hampered by all the nonsense in schooling, bottom line is check the providence and ask whether they gave experience, what their results are, do they know the exam inside out (examiners or ex-examiners are obviously the best choice) and then see if they actually help the student rather than just leaving them to it, a tutor is a support not a panacea! I really hope that helps!