Having tutored both children and adults, my experience is that achievement will come as we establish (perhaps re-establish) your confidence in the subject or area.
Similarly, be strong in the basics. This will come with a certain amount of repetition.
Let's take Maths. In the same way that all dance has it's roots in ballet, all Maths (formulae, algebra, equations, geometry, fractions) has its roots in the four basics of addition, division, multiplication and subtraction.