In English Literature essays the best way to ensure that the quotes you use are relevant (therefore mark worthy) is to group quotes when learning them. Analyse the book, assess four to six main themes or ideas and group your quotes in this form of categorisation. This means that when you are answering the essay question you can tell by reading the question which category of quotes will be most relevant. Grouping them can also be a useful visual aid to actually learning them in the first place. I personally found that using a specific colour and category for the quotes of a specific theme helped me to ensure that I not only knew the quotes by memory but could also comment critically on their relevance to the text as a whole.