I studied 'Of Mice and Men' for GCSE and got an A, and continued to study until A-level where I also worked at A grade. From my experience when using quotations, for example, 'broken', you should be talking about the adjective Steinbeck uses to portray the character of Crooks to the reader and why he makes such vocabulary choices.
I would say 'Steinbeck uses adjectives such as 'broken' and 'tattered' when describing Crooks' possessions, suggesting not only that he does not take pride in material things, but also connotates imagery of Crooks himself and his unkempt appearance. It allows us to sympathise with Crooks as a modern day reader, illustrating to us the attitudes surrounding racism and the monotonous stigma associated with black citizens in their minority in the 1930s. Steinbeck is merely reflecting Crooks' 'broken' attitude towards life through his appearance and surrounding possessions.'
It is important to remember that the examiner knows the story. You are not writing to tell them what happened in the novel, but to pinpoint the techniques Steinbeck used in order to make it effective. Your focus should be on the range of terminology you pick out and relating it to the question. Picking out quotations may seem easy, but it is how you expand upon those quotations (make something out of nothing!) that shows your depth of understanding. Make sure you only use terminology you are comfortable with the meaning of - don't go using words just because they sound good without understanding what they are. This will only hinder you and waste time when you could be making valid points. Try to say 'the adjective 'broken'' or 'the list of three *insert quotation* to ensure that you are saying something about the technique used by Steinbeck and how this enhances the novel. Even if you don't like the novel - pretend to. The fancier you sound, the more it sounds like you know what you're talking about, so expand your vocabulary and brush up on terminology so you know what you're talking about! Also try to vary your structure slightly. I know every class is taught differently, but there is no harm in putting context at the beginning, middle or even end of a paragraph. Just integrate relevant information, keep it precise and don't go off on a tangent!
The basis is there - your writing is confident. All I can suggest is to submit as many pieces of writing to your teacher as possible before the exam. Get her to set you a list of questions and write 1 point on each. Don't forget your introduction and conclusion too. It's a lot to do in a little time so practice being concise and cram as much in as you can!
Good luck and I hope this was helpful!