You are not allowed to eat satiating food from the beginning of the tenth hour on Erev Pesach. This is so you can build up a hearty appetite to eat matza at night. (ShA1)
What is considered satiating food? Anything that contains one of the five grains. Also, a little bit of wine satiates. (ShA1 — MB3)
The following foods are allowed even from the tenth hour as long as you do not fill up: fruit, meat, fish, eggs, vegetables. (ShA1 — MB3 — ShaH5)
It is forbidden to eat matza (that is kasher for the Seder) from dawn on Erev Pesach. Some minhagim forbid it from Rosh Chodesh Nissan. (Rama1 — MB12)
Do not feed matza to children who begin to understand the stories that will be told at Seder night. (MB13)
Matza meal products on Erev Pesach: (1) Plain matza meal is ossur; (2) Matza meal mixed with oil or wine and still raw — also not to be eaten; (3) Matza meal mixed with liquid and then boiled (like knaidlach) is allowed before the tenth hour; (4) If you fry the batter, some poskim are maykil. (Rama2 — MB20 — ShaH20)
It is a mitzva to get haircuts on erev Yom Tov. After chatzos go to the mikva, daaven Mincha, and learn the laws of Korban Pesach. Hashem will consider it as if you actually offered it. Get dressed into fancy clothes like on Shabbos. (Rama3 — MB22)
