As somebody who likes to teach math privately to people I recommend one thing first and foremost: Intuition. In mathematics, intuition is often thrown under the carpet as distracting from playing with mathematical concepts but in order to understand mathematics, you need to understand WHY people made formulas the way they do. As a result, students often have a 'see monkey, do monkey' mentality while having no true understanding of the topic. People with even less understanding aren't even able to replicate the desired results.
In general, the less the student has a feeling for mathematics, the more you need to teach intuition first and formulas later. Math students are of course required to have a higher level of understand, but this is obvious.