1. Customs on Erev Yom Kippur

(a) To immerse oneself in the Mikveh
(b) To give Tzedakah (charity)
(c) To say the Vidui (confession) at Minchah
(d) To eat a Se'udah Mafseket (pre-fast meal)
(e) To bless one's children.

2. Mitzvot in the Torah, according to Sefer Hahinukh .

213 To fast on the 10th of Tishrei.
214 To offer an additional sacrifice on Yom Kippur.
215 To abstain from melachot (certain acts of occupation) on the 10th of Tishrei.
216 Not to eat or drink on Yom Kippur
217 To abstain from melachot on Yom Kippur.
264 Vidui (to confess one's sins).

3. Five abstentions included in 'tormenting' (or humbling) the soul:

(a) Not eating or drinking
(b) Not washing
(c) Not annointing the body
(d) Not wearing leather shoes
(e) Separation from one's wife (husband).