An abridged version of Selichos is said on Erev Yom Kippur, and During Shacharis, Mizmor L'sodah, Tachanun, and Lamenatzei'ach are omitted. Avinu Malkeinu is recited this year (as Yom Kippur coincides with Shabbos).
The minhag of Kapparos should be performed with proper concentration and thoughts of teshuvah. Ma'aser funds should not be used.
There is a mitzvah to immerse in the mikvah on Erev Yom Kippur. Some say to immerse oneself three times, while others say seven times. It is best to go to the mikvah no earlier than one hour before chatzos but before one davens Mincha.
One should daven Mincha on Erev Yom Kippur before the Seudah Hamafsekes, so that Mincha's Viduy is recited before the Seudah Hamafsekes. A woman who will not be davening Mincha should still recite the Viduy.
There is a mitzvah to eat on Erev Yom Kippur. Rabbeinu Yonah cites three reasons: 1) To display our simchah over our upcoming atonement. 2) A seudah on Erev Yom Kippur substitutes for the Seudas Yom Tov that we obviously cannot have on Yom Kippur. 3) To give one strength for the fast. Note that one who isn't thirsty and is drinking water solely for hydration does not make a berachah.
The Seudah Hamafsekes may be eaten any time after Mincha. There is no obligation to wash and eat bread at this seudah, but there is a custom to eat kreplach at this meal. Preferably, one should verbally state (or at least have in mind) before saying Birchas Hamazon that he does not intend to begin fasting at this point and will continue eating and drinking.
The home should be prepared and cleaned for Yom Kippur as it would be for Shabbos, with a tablecloth set on the table. One should dress in Shabbos clothing, yet the attire should reflect the day's tone. Some have the minhag to wear white garments and not to wear (yellow) gold jewelry.
Parents should bless their children before setting out to Shul.
A 24-hour candle is lit for the Havdalah flame on Motzaei Yom Kippur. Many have the minhag to light a Ner Neshama due to Yizkor. One should remember to fulfill his Tzedakah pledges from the Yizkor. Some also have the minhag to have a lit candle in their bedroom ("gezunte lecht").
The tallis is worn during all tefillos throughout Yom Kippur. One should don his tallis on Erev Yom Kippur before shekiya, as the berachah on the tallis may not be recited at night. Most wear a kittel as well. There is mitzvah d'oraysah (mentioned in Tefillas Zakkah) to add to the day of Yom Kippur by accepting the arrival of Yom Kippur upon oneself a bit earlier. Since Yom Kippur is also Shabbos this year, the berachah on candle lighting is "l'hadlik ner shel Shabbos V'shel Yom Hakippurim".
