Nick Hern Books
A very handy pocket-sized book written by a highly-experienced actor (leading roles at the National Theatre and in West End shows) who went on to become a renowned expert in memory improvement. The book is an easy-to-read and entertaining guide to learning lines using several techniques, including the 'Memory Palace' approach. If you haven't come across this before, it dates back to Ancient Rome and Greece and involves memorising objects in a building or room that you are very familiar with. This effective approach is widely used, but what makes this book particularly useful is the way it is applied to learning lines for performance.
Using the experience of his acting career, Mark Channon applies his approaches (also including mindfulness, breathing, body-scanning and many others) to learning lines for auditions, rapid learning for television shoots, getting off-book in rehearsals and becoming present and truthful in your relationship with other performers. He uses practical examples as well as stories of his own experiences to discuss how to approach scripts, deal with nerves and create confidence.
The approach is very different to many I have come across previously and I highly recommend trying some of his creative and left-field ideas.