Revising for non-fiction can be really hard and many people insist that you can't really revise for anything. Here are a few things i would recomend remembering and using in your exam...
T- type (what type of text is it e.g letter, article, speach, leaflet)
A- audience (who is the text aimed at e.g the age group)
P- purpose (what is the point of the text/ what is it trying to do e.g persuade, advise, inform, argue)
When writing or reading texts, ALWAYS ask yourself WHY has this been used and HOW has it been used. This will not only help you to develop your answer but to also show that you are able to analyse.
Make sure you are including the writers intention and also the effect the text has on the reader.