Psicon Adult Mental Health Services recommends Paul Gilbert’s book The Compassionate Mind.
Half the book is on the very compelling scientific theory behind the practice and the other half offers exercises to help you become more compassionate. The basic idea is that we spend most of our time either neutralising threats or striving for success and not enough time being compassionate to ourselves. Many people struggle with this but a lack of it can mean living with distressing emotions. It’s an easy read and written in a very engaging, practical style.