In the city of Radin, on the day a bachur had to sign up for the Polish army, the bachur would daven shacharis with the Chofetz Chaim (who had a private minyan in his home), and after shacharis, the Chofetz Chaim would give the bachur a brachah that he be saved from the army in the merit that he accepts on himself the yoke of Torah.
Reb Naftali Trop zt'l was the rosh yeshiva in Radin, and his son, Reb Reuven, was summoned to the army. That day, he didn't daven shacharis with the Chofetz Chaim or seek his brachah. Reb Reuven had recently suffered from tuberculosis, r'l. He was thin, appeared unwell, and was confident the army would reject him. But the army signed him up for service. He was the only bachur drafted from the entire yeshiva. Reb Reuven told his father what occurred. Reb Naftali told him, "That is how it is. When one doesn't place his trust in Hashem, even if he is dangerously ill, he will be drafted to the army."
Segulah for Shidduchim
The Midrash (Bereishis Rabba 68:2) says, "When Yaakov went to Charan, by his father's command, to find a wife, Elifaz (Eisav's son) came and took away all of his money. At that time, Yaakov said אל עיני אשא למעלות שיר עזרי יבוא מאין ההרים. Saying this kapitel of Tehillim before one takes three steps back after Shemoneh Esrei has become a segulah for finding one's shidduch easily."
Why is this chapter, in particular, mesugal for shidduchim? Perhaps we can explain that this chapter expresses the fears of a person who doesn’t have any idea עזרי יבא מאין, where he can receive his salvation. He feels lost. But he knows that his only solution is 'ה מעם עזרי, that Hashem will help him. And when one attains this awareness, he merits salvation. Accordingly, this chapter isn't solely a segulah for shidduchim. It is a segulah for all one's needs.
Kiddush Levanah and Shidduchim
The Kaf HaChaim (426:10) writes that being careful always to recite kiddush levanah with kavanah and with a minyan is a segulah to find a shidduch. A hint to this idea can be found in the word לבנה, moon, which is roshei teivos of הרביעי ליום נשאת בתולה, a besulah gets married on Wednesdays. (These are the first words of Masechta Kesubos and hints at the concept that kiddush levanah is mesugal for shidduchim and marriage.)
