How many quotes do I need to learn from (relevant book title)?

There is no right or wrong answer to the amount of quotes you need to learn. It's not about who can memorise the most words from the book, but rather who can understand and discuss the key themes in the book, and use the quotes to highlight, or further understand these themes. my advice would be to figure out the key themes/motifs and characters in the book and identify 3 or 4 key quotes for each, and try to choose short and easy to memorise ones. It is often also possible to choose quotes which are applicable to many themes. It is good to have a few very specific quotes, but generally applicable ones are always a winner. Try to have your quotes perform a different function also, for example there's no point having two quotes demonstrating (how a character expemplifies a certain theme) one will be sufficient.