The most thorough analysis of this problem is in Isaac Luria.
1) The first place to start from is clearly Plotinus. He has identified the Good with the One of Plato. And in his framework it is easy to get to the idea that the farther one is from the One, he is closer to evil. This make physical desires closer to evil than is generally understood in the U.S.A.. At least with Plotinus we do not get the fulfillment of ones physical desires to be identified with the good. That is something Plato already knocked clear out of the water. Isaac Luria does us all a great favor by putting Plotinus together with the pre-Socratics to have a highly powerful self consistent system.(Its flaw is it is dressed in highly mystical terminology. But as a philosophical system it is as sophisticated as Hegel and maybe more so. And I think Luria avoids many of the pitfalls that Hegel fell into.)
So with Luria we get what looks much more like a realistic account of evil that the simple physicality approach of Plotinus which frankly is a powerful system but does not take into account that Platonic forms might also account for evil.
At any rate, with Isaac Luria at least we are finally getting somewhere. We have got the Tzimum [(צמצום) contraction of the Infinite Light] plus the Kelipot ("shells" forces of evil) caused by the breaking of the vessels [of nekudim (נקודים)][which as part of the correction eventually became Emanation (אצילות).]
This results in two separate types of evil, one from the contraction [tzimtzum] and the other from the kelipot. [Kelipot are basically when the light hit the vessels of emanation and broke them and the pieces of the vessels fell.] three major groups of evil: Dimion [delusion], physical animal desires that have not be absorbed into holiness. [Desire for honor is also an animal desires as we see by all groups of primates] (3) Evil that stems from the original contraction of the Light.
The there is the holy angel [Satan] which in this scheme seems to stem basically from the world of the Kelipot.
the higher one goes in spiritual growth, the stronger is the evil inclination.
[Schopenhauer has a different account, but I did not find the time here to go into his account. Schopenhauer in any case is best as a modification of Kant. They both ought to be learned together.
In any case, Schopenhauer puts evil right smack into the Will. And only in a latter letter admits that in the final analysis the will itself has a higher aspect of the Good like Plato thought..
At any rate, this brings me to the end of this discussion and the question of how to deal with evil. \ the higher one grows in spirituality the stronger and more subtle his evil inclination becomes, he can't give much of a solution except to go to a a wise man and get advice. [Now this might sound like a "cop out" but it is not. . To him, getting advice from people that are not themselves holy is the cause of evil in the world.]
But how does this help us? We already know people that claim to be holy or whom their followers claim to be holy are often the exact opposite.
Israel Salanter's idea might be more practical.
But Israel Salanter may have hit upon the germ of an idea that can answer this question. He noticed something unique about books concerning fear of God that were written during the Middle Ages. Books concerning philosophy during the Middle Ages have something that books written do not have. They avoid circular reasoning. Circular reasoning seems to be a plague affecting all philosophy from David Hume and onward. [Hume excelled in circular reasoning. (Taking apart Hume) Not only does it affect all is major ideas but he seems intent on putting it into every single chapter that he writes.] On the other hand Medieval books do have a problem of accepting as axioms things that today we would consider not true.
Now gaining Fear of God is not directly related to the question of evil since we know Satan disguises himself in mitzvot. He never comes and says lest do something wrong. When Satan wants to trap a person in some scheme he comes and says lets do a mitzvah and then shows you why it is a mitzvah.
However Medieval books about the fear of God do one very important service- -the issue of world view. and we already know that world view issues are even more important that issues about physical pleasures.