From the sources (about the Maaser):
As we have said above, the Maaser is an ancient custom of Kabbalists. Below are a number of authentic sources concerning the Maaser:
“Thou Shalt Surely Tithe” (Rav Baruch Shalom Ashlag)
From The Steps of the Ladder, article no. 553
Thou shalt surely tithe. And they explained, “tithe, so you will become rich.” This is perplexing; how did our sages explain the necessity of the verse with Lo Lishma (not for Her Name), that is, that he will give charity so as to become rich. We should explain it as they said, “We shall do and we shall hear.” This means that through the act they will achieve hearing, that the act affects the intention.
It follows that during the giving of the Maaser, meaning a Maaser of giving, he will aim to become rich, that is, to be rewarded with a desire and craving to give, meaning as the act is giving and not receiving, his thought and aim, too, will be only to give and receive nothing in return.
And we should also say… if he performs an act of giving… he will be rewarded with the aim, too, becoming giving and not receiving.
And what will happen afterwards? “so you will become rich.” This is because it is impossible to receive the delight and pleasure, called “wealth,” from the Creator before one has equivalence of form. At that time, when he is rewarded with the intention being in order to bestow, as well, he will be rewarded with receiving the wealth.
From From Concealment to Revelation, article no. 216.
He should give charity in order to become rich, so that through the act he will achieve “hearing,” since the act affects the aim. In giving Maaser, an act of giving, one should aim to be enriched and be granted desire and craving to give, the intention only to give and receive nothing in return.
Rabbi Akiva said about the Maaser (Mishnah, Masechet Avot): “Tithing is a qualification for wealth.”
The Vilna Gaon: “Who keeps Maaser is guarded from harm.”
You may also read Masechet Maasrot (in Hebrew) from the Jerusalem Talmud”