Our lives are mainly spent getting to know ourselves and others through our relationships and all of our relationships can be improved. Even a hermit needs to have a good relationship, not only with the local animals and birds and insects, but with himself (hermits are almost exclusively male!).
My first advice to anyone seeking to improve their relationships is to become aware of your relationship with yourself. Being a part of a loving relationship is one of the most satisfying and valuable things possible. However, it is impossible to have a successful relationship with anyone else if you do not first have a successful relationship with yourself.
To have a successful relationship with another person, you must first love yourself and that can be surprisingly difficult for many reasons. For most people, the idea of loving yourself smacks of the worst kind of egotism. Upon closer examination, it becomes apparent that here is yet another example of the wisdom of the Golden Rule: Do unto others that which you would have them do unto you. Love other people the way you would have them love you and love yourself the way you would like to see other people love themselves. What a wonderful world this would be if everyone loved themselves, filled themselves with love and self esteem and when they loved another person, it would be for all of the right reasons.