103:2 How do we honor yom tov? Our Sages explain (Moed Katan 14b) that it’s a mitzvah for a person to get a haircut before yom tov in order to not enter the festival looking unpresentable. It’s also a mitzvah to bathe in hot water, to comb one’s hair and to cut one’s nails before yom tov, the same as it is before Shabbos. It’s also a mitzvah to knead bread in one’s home in honor of yom tov, the same as for Shabbos. Similarly, one may not eat a meal on the eve of a Festival starting from the time of the afternoon prayers, just like on Fridays before Shabbos. This is so that one will be able to eat the yom tov meal with an appetite. If yom tov starts following Shabbos, one should eat the third Shabbos meal before the time of mincha katana (“small mincha,” i.e., nine and a half hours of the day – refer back to 69:2). This is also true of the first day of yom tov, which is the eve of the second day of yom tov. (It’s not so clear that that last point is correct, that one should refrain from eating on yom tov when he is hungry – Bi’ur Halacha 529:1 s.v. b’erev yom tov.)
103:3 What constitutes enjoying yom tov? The Sages explained that a person is obligated to eat two meals – one at night and one during the day – on each day of yom tov. (If a person neglected to eat a night meal, he should eat two meals by day – Mishnah Brurah 529:13.) The custom is not to eat a third meal on yom tov as one does on Shabbos (though one should eat a snack – ibid.). One must recite kiddush over wine before the meal and HaMotzi over two whole loaves as one does on Shabbos. One should eat more meat, wine and delicacies as he is able.