You could ask Google as well as other parents and teachers for their word of mouth recommendations.
 
You’ll find dozens of tutoring agencies in your city and you should follow up with some calls to understand their approach.

At Top Schools, we work with a very small number of trusted agencies and we are happy to recommend. We will never be prescrptive and suggest any particular agency; you should explore 2 or 3 and choose the one that feels right for you.

On the whole, we tend to prefer online tutors based in the UK if your child suits this mode. The sheer number of tutors available there means that the quality is top notch and, if aiming for a UK school, they know the system and the format of the various tests inside out and backwards.

However, if you prefer a tutor based where you are, we can arrange for face to face tutors too.