Hiring a Tutor
Don't go searching for a tutor on a classifieds site. The tutors there are not checked by anyone in any way whatsoever.
Think if you actually need a tutor, and don't force one on your children. Tutoring for the 11+ is ill advised. I believe it is a waste of money - not as effective as making a student go though practice papers themselves.
Don't use an agency. They are not regulated. I have heard of agencies charging £500 to register you. After this the will charge you for every lesson arranged, no matter how unsuitable the tutor Most freelance tutors will expect to be paid per hour with no arrangement fee.
The best tutor is often one recommended by a friend. Hiring them is almost painless, if they will do it. This should not stop you asking any questions you need to ask.
Look ahead. If your child wants to study a subject at GCSE and later A Level or Degree, look for a tutor with the qualifications to teach them up to the highest level they want to study.
Ask them how they are arriving. I often find parking a problem. Tell them if train or car is the best arrival route.