The study of Jewish mysticism, the Kabbalah, presents a special problem.
Though the Kabbalah is probably the only extant Jewish theological system, there are various attitudes to its study, which question not the relative value of studying Kabbalah, but the qualifications necessary to undertake it.
It is very important to recognize that, unlike other mystical doctrines, the Kabbalah is not a discipline unto itself but is closely linked to mainstream religious practice.
It is in a sense a commentary on both the written and oral Torah, and cannot be separated either in theory or practice from the full panoply of the mitzvot.
There are relatively few places where Kabbalah can be studied properly, and the secondary literature available on the subject tends to be superficial, un-Jewish, or even anti-Jewish.
While recent rabbinic authorities have ruled that study of "the doctrine of hidden things" need not be suppressed, it is nonetheless advisable to avoid getting into mysticism in an unbalanced way.
One drawn to Judaism along the mystical path should take special pains to study halakhah as well, particularly the Talmud and its commentaries, both in order to better understand the Kabbalah itself—a connection a number of well-known scholars have underscored—and in order to keep one's balance and avoid going astray.
It is false and misleading to view the Jewish mystical tradition apart from the larger context of Judaism as a whole.
–Rabbi Adin Steinsaltz
From "Talmud Torah" in Teshuvah by Rabbi Adin Steinsaltz