Learning from the Tanya offers a key for unlocking the mysteries of one of the most extraordinary books of moral teachings ever written. A seminal document in the study of Kabbalah, the Tanya explores and solves the dilemmas of the human soul by arriving at the root causes of its struggles. Though it is a classic Jewish spiritual text, the Tanya and its commentary take a broad and comprehensive approach that is neither specific to Judaism nor tied to a particular personality type or time or point of view.
This is a thorough introduction to the Tanya, a Jewish guide to a soul's potential and responsibility in the world. I read this when I couldn't sleep but probably didn't take it seriously enough.
There are tons of notes and commentary on every passage of the Tanya chapters 10-26 by Rabbi Steinsaltz. There is another set of books called LESSONS IN TANYA which is the preferred choice in Lubavitch yeshivas. LESSONS IN TANYA contains inciteful translation and commentary in English and includes the original Hebrew text (the Steinsaltz includes only the Hebrew translated into English). If you can't consult with a local Chabad Rabbi, Reb Steinsaltz has a handy extra perspective.
This guide really breaks things into "absolute/fundamental" terms which when taken loosely is helpful in personal soul searching (at least diagnositically) but too sharp and overwhelming to live by.