Rav Haim Vital (1543-1620) would immerse in a Mikveh on the day before Purim, just like on Ereb Yom Tob, and this is an admirable practice to observe.
One should change into Shabbat clothes already on Purim night. Some people wear Shabbat clothes only during the day of Purim, but this is improper; Shabbat clothes should be worn already on Purim night, as the special spiritual light of Mordechai is upon us once Purim begins in the evening. Women, too, should change into their Shabbat clothes, and wear jewelry, on Purim night and wear them throughout Purim day. This Halacha is mentioned by the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in his work Ateret Tiferet.
The Shulhan Aruch rules (Orah Haim 695:1) that one does not fulfill the Misva of the Purim feast on Purim night; the meal must be eaten specifically during the day of Purim. Nevertheless, the Rama (Rabbi Moshe Isserles of Cracow, 1525-1572) notes that there is a Misva to have a somewhat festive meal even on Purim night. It is customary to eat seeds on Purim night, as Ester ate seeds in Ahashverosh’s palace, since she could not eat the meat. Furthermore, Daniel – who, according to some opinions, was Ester’s messenger, Hatach – ate seeds while he served under the Babylonian emperor Nevuchadnesar.
One should be especially careful to avoid fighting and discord throughout Purim, both at night and during the day. The flurry of activity that characterizes the Purim celebration can oftentimes create pressure and tension in the home, and it is thus crucial to make a special effort to exercise patience and forbearance on Purim, in order not to disturb the festive atmosphere.
Additionally, one should make a special effort to make time for Torah learning on the night of Purim. A famous verse describes that at the time of the Purim miracle the Jews experienced "Ora Ve’simha" – "light and joy" – and the Sages teach that "light" refers to Torah study and "joy" refers to festive celebration. "Light" is mentioned before "joy" because the "joy" – the Purim festivity – is observed during the day, and thus the "light" – Torah learning – should be done the previous night. It is therefore proper to spend Purim night engaged in Torah learning, since there often is not much time available during the daytime for learning.
More generally, the Hida (Rav Haim Yosef David Azoulai, 1724-1807) commented that if the Jewish people would conduct themselves with sanctity on Purim day, rejoicing for the sake of Heaven and then spending time learning Torah, we would immediately earn redemption. Most people, unfortunately, do not allocate time for Torah study on Purim, and this itself is reason to make an effort to spend time learning on this day. The Sefer Hasidim (work by Rabbenu Yehuda Hahasid of Regensburg, Germany, late 12th-early 13th century) teaches that one should make a special effort to fulfill Misvot that few others fulfill, and one will thereby earn great reward. Thus, it is appropriate and worthwhile to try to spend time studying Torah on Purim, as it is a day when few people make a point of fulfilling this Misva of Torah learning.
