When I helped out at the tutor group during sixth form, the best way I found to teach was to let the student work through a problem they are finding tough and then to pick apart what might be going wrong. This means that the exact gap in understanding can be identified, often making an entire concept click. The key to success in mathematics is effective practice, such as cherry picked textbook questions and exam papers. This ensures a deep level of understanding, as oppose to just reading the textbook or making flashcards. This however is a good start as it is important to know the base content of a mathematics course well so that the starting point of tricky problems is clear. I believe that the time spent practicing the maths should vastly outweigh the time spend memorising, as valuable lessons and improvements of understanding are gained by working through problems (even if the solution goes wrong!). I believe that working through a tricky problem and making mistakes is an excellent teacher, so in my lessons you will tackle tricky problems with my guidance until you can work through them in a logical, methodical manner. However I understand that different students are aiming for varying grades, and if a student is simply trying to pass (whilst I will do my best to instill the best possible mathematical understanding) often time can be wasted on problems that only need to be solved if you are aiming for an A*, whilst ignoring the bulk of exam questions targeted towards B or C. With this being said, once a good understanding is in place, any problem is possible with enough practice.