As a private Mathematics tutor I also get asked this question a lot. I often get interrupted whilst explaining the concepts of Trigonometry or Algebra with a groan or two followed by an admission of defeat and that the student will never remember anything that I have taught them because there is simply too much to remember. The answer to this is very simple, in one word practice.
Remember learning to ride a bike? Well you may have got it first time round if you were lucky! Or if you were like me you kept falling off your bike until you eventually got it! Well Mathematics is very similar to that. Ok well you don’t ride a bike but the principal is the same as much as it is a procedural activity. When you ride a bike you get on the saddle. Then you put your feet on the peddles, then begin to peddle finding your balance etc. Well in Mathematics it is very similar when solving an equation for example. You start off by writing out the equation then begin to balance the equation eventually arriving at a single variable equal to a number. So here you have followed a set procedure to solve the equation.
The more questions that you do the more natural it will become for you to solve equations, just like riding a bike! It will become almost habitual when presented with an equation. Remember when revising for your GCSE Maths exam you can use the GCSE maths master revision DVD to help refresh your memory, the ultimate aid for GCSE Maths revision.