Letters from a Stoic — Seneca

No one truly has all the answers to life, but Seneca may come close. Stoicism is a way of interpreting the world with an intentional manner of calm - this book contains a series of letters from Seneca outlining the basic principles & application of stoicism. 

One of the first piece of advice he gives in this collection of letters is to read well-tried authors - if you read this book, you'll already be following his advice.