The Arizal says one who stays completely away from the slightest amount of chometz the whole Pesach is assured they won’t sin a whole year. (Chometz is an allusion to the sitra acher. It is brought down from Reb Chaim Vital that any aveira one does on Pesach is worse than if done the rest of the year. We could assume that the reward for staying away from sin is also greater than the rest of the year. Putting these together, perhaps what the Arizal means is, if one stays away from the sitra acher, not sinning at all on Pesach (including not eating any chometz), then he has this assurance.)
Reb Naftali of Ropshitz in Zera Kodesh says that Pesach is a segula for parnasa since on Pesach the crops are judged. The Chidushei Harim says the same thing and adds another reason; because earning a living is considered as difficult as Krias Yam Suf, the splitting of the sea, which occurred on Pesach.
It is a good to burn arovos leftover from Hoshana Rabbah (though some aravos should be kept as a shmira) together with the chometz. This destroys “evil forces”. (Kav Naki to Kav Hayosher, based on Yesod Yosef)
There is a segula from Reb Shimson Ostropolier ZY”A (great-grandfather of Toldos Yaakov Yosef & R’ Lieber of Berdichev) to read a fascinating letter he wrote on the Arizal’s sefer about the 10 plagues of
Reb Nachman of Breslov says that a kezayis of maror on Pesach is a segula for parnasa. (Sefer Hamidos) Reb Nachman of Tcherin explains this is because it says in Masechta Eruvin that the dove sent by Noach said: “Ribbono Shel Olam yehiyu mezonosai marorem kezyais beYodecha” – “Master of the universe may my food be as bitter as an olive but dependent on You” (rather then sweet as honey but dependent on flesh and blood).
The Kav Hayoshor says that matza is a shmira like a mezuzah. There is a minhag to save a piece of the afikomen as a segula for shmira. The Orchas Chaim says that it protects from robbers and from “bad forces” because MaTzaH stands for M’kol T’zarah H’atzileinu (from all suffering save us), and it is even better if you save a piece from the matza that you recited 2 brochos on by Motzei Matzah.
Before the Mah Nishtanah it says in the hagada (and this is also what it says in Talmud Yerushalmi)“v’kan haben shoel”. This can be read as: “and here ask for a son”. This is a time that is mesugal for someone who has no children or only daughters to ask Hashem for a son, so that he can fulfill the mitzvah of “v’higadita l’bincha”, telling over to your son the story of the Hagada.
It is brought down in Sifrei Chasidus that the seder night is mesugal to speak to children about the Hagada and emunah even if they are little babies, since it goes into their neshama.
Meor V'Shemesh says that the eating of matzah on Pesach protects the neshama from being damaged by chometz during the year.
Shabbos After Pesach
It is a segula for parnasa to bake shlisel (key) challah for this Shabbos. The Ohev Yisroel explains one of the reasons is because it’s Shabbos Mevarchim Iyar, and Iyar is when the mon started to fall. There are customs as to how this is done including putting a key into the challah before baking, making the challah in the shape of a key, making a key out of dough and placing it on the challah or putting sesame seeds on the challah in the shape of a key. Reb Pinchos of Koritz says to make the challah flat to look like matzos. There will be a separate post about shlissel challah after Pesach. Here is that posting.