To truly understand Kabbalah and be a competent Kabbalist, one must know the meaning of the Hebrew letters. Therefore it would be good to study: The Alphabet of Kabbalah
Regarding the Tree of Life and its antithesis, the following four courses referenced below are essential. Either of these would be a good start to comprehending the Kabbalah. Then, the science of the Hebrew letters will help you go deep into the meaning of the Judeo-Christian scriptures.