Shir HaMaalos
The Midrash (Bereishis Rabba 68:2) states that when Yaakov Avinu sought a shidduch for himself, he said Tehilim chapter (121) שיר עזרי יבא מאין ההרים אל עיני אשא למעלות, "I shall raise my eyes to the mountains, from where will my salvation come?" At first, he was worried, עזרי יבא מאין, "From where will my salvation come?" He said, "When Eliezer went to bring Rivkah, it states (24:10) גמלים עשרה העבד ויקח, that he came with a lot of wealth. But I don't even have with me one ring or one bracelet?"
But then he said, "What? Should I lose hope in my Creator? Chas v'shalom. I will not lose hope. ינום אל רגלך למוט יתן אל ...'ה מעם עזרי ישראל שומר יישן ולא ינום לא הנה .שומרך, My help is from Hashem... He will not allow your foot to falter. Your Guardian will not slumber. Behold the Guardian of Yisrael will neither slumber nor sleep."
In the merit of this chapter of Tehillim, Yaakov Avinu found his shidduch, Rachel, and therefore, the Rema m'Pano says that when one needs a shidduch, it is a segulah to say this chapter of Tehillim before the final רצון יהי at the end of Shemonah Esrei.
The Bnei Yissaschar writes that this segulah is ומנוסה בדוק, tested and proven to be true. It is a wonderful segulah for attaining one's shidduch.
The Kaf HaChaim (426:10) says that saying kiddush l'vanah with joy and kavanah is mesugal to find one's shidduch. The hint is that ה"לבנ is roshei teivos for יוםל שאתנ תולהב רביעי ה, "A virgin gets married on Wednesday" (which are the beginning words to mesechta Kesubos).
And certainly, one should daven for one's shidduch. Dovid HaMelech urges us in Tehillim to daven for a good shidduch. The Gemara (Brachos 8.) quotes the pasuk (Tehillim 32:6) מצא לעת אליך חסיד כל יתפלל זאת על, "For this let every pious man pray to You at the time that You are found." The Gemara says לעת אשה זו מצא, that מצא לעת refers to that one should daven for a wife, as it states (Miishlei 18:22) טוב מצא אשה מצא, "When one finds a wife he found goodness."
Another hint at the importance of tefillah for a wife is (24:63) בשדה לשוח יצחק ויצא, "Yitzchak went out to daven in the field."
When Eliezer arrived, he told Yitzchak about how he found Rivkah and the many miracles that occurred, as it states (24:66) ויספר עשה אשר הדברים כל את ליצחק העבד, "The servant told Yitzchak all the things that he had done."
Rashi writes, "He revealed to him the miracles that happened to him, that the earth jumped for him, and בתפלתו רבקה לו שנזדמנה, that he found Rivkah while he was davening."
The simple meaning is that as Eliezer was davening to find a shidduch for Yitzchak, Rivkah arrived, as it states (24:15) טרם הוא ויהי יצאת רבקה והנה לדבר כלה, "And it was that before Eliezer finished praying, that Rivkah came forth..."
The Chasam Sofer zt'l explains that when Rashi writes בתפלתו רבקה לו שנזדמנה, that he found Rivkah while davening, it isn't referring to Eliezer's tefillah, rather to Yitzchak's tefillah. When Yitzchak davened, that was the moment that Eliezer arrived with Rivkah. בתפלתו רבקה לו שנזדמה means that the moment Yitzchak davened for his shidduch, that was when the shidduch arrived.
The Chasam Sofer adds that this is the reason there was kefitzas haderech while traveling to Charan, but there wasn't upon returning. Eliezer couldn’t return too early because there first had to be Yitzchak's tefillos.
