OK, it depends on how you think.
Are you a word person? - do you study and learn better when things are written down in words
Are you a picture person? - do you study and learn better when you draw little diagrams and pictures and graphs and such to help you understand
Are you a verbal person? - do you prefer to hear it explained
Are you a doing person? - do you like to do something to understand what is happening
When you know your style of learning, then you can start to fix your understanding. If the teacher is explaining and you are a picture person, you need her/him to DRAW a diagram as he/she speaks. Or you need to try and draw one. If you learn by doing, then you need to work out some way to visualise or do the thing that is being explained.
Decoding questions, though, is another thing. If it is a written answer (ie words) then you need to understand what the key words mean: explain, discuss, describe etc. These are available from the Board or Studies webiste or even at the back of the Physics syllabus (also available at the BOS).
If it is a number question you need to pull out the numbers as you read them. If the questions talks about the amount of charge and find the resistance and gives you a time and voltage, on the right hand side of the page write the information in a little "Info box". R = ?, q = 3 C, t = 45 s, V = 3 V
Using that, you then look at the formulae you know and see what ones you can use to find the required outcome.
If you are worried about not knowing stuff that is off syllabus but related that is simply a matter of being better read and watch more science shows and such. Mythbusters is a good one (as suggested), Catalyst, and those sorts of things.