Just as there is a mitzva on Shabbat to honor it (kavod) and to make it a delight (oneg), so too there is a mitzva to honor and delight in Yom Tov (above, 1:7-8).
Therefore, everything which the Sages instructed us to do in preparation for Shabbat must be done for Yom Tov as well. This includes washing one’s clothes in anticipation of the festival (Peninei Halakha: Shabbat 2:4; below 11:11), as well as taking a hot shower. It is also a mitzva for one who needs to get a haircut, shave, or cut his nails to do so (ibid. 2:5; below 11:9-10). Cleaning and straightening up the house before Yom Tov is also a mitzva, and men should participate in these preparations, as was the custom of great rabbis (ibid. 2:5-6).
To fulfill the obligations of delighting in the festivals and enjoying them, there is a mitzva to buy good food and drinks in their honor, each person in accordance with his means (above 1:12). One may not sit down to a large meal on the day before a Yom Tov, for three reasons: first, a weekday meal should not be equated to a festival meal; second, so that one has a hearty appetite for the Yom Tov nighttime meal; third, the effort involved in preparing a meal for before Yom Tov can detract from Yom Tov preparations. In contrast, a normal meal may be eaten at any point during the day. Nevertheless, le-khatḥila the Sages say that it is preferable to avoid having a regular meal, or one with bread, during the three hours before the start of the festival (Peninei Halakha: Shabbat 2:7).
On the day before Yom Tov, one may not work from Minḥa time and onwards. If one chooses to work then nevertheless, he will have nothing positive to show for it. This prohibition starts from the time of Minḥa ketana, meaning two and a half (seasonal) hours before shki’a (sunset). The details of these rules are explained in Peninei Halakha: Shabbat 2:8.
We begin Shabbat a bit early (before shki’a) and end it a bit late (after tzeit ha-kokhavim) in order to add to the holy from the mundane. We do this for Yom Tov as well (RH 9a). Yom Tov is accepted either verbally, with a statement along the lines of, “I hereby accept upon myself the sanctity of Yom Tov,” or by lighting the Yom Tov candles (MB 261:21; Peninei Halakha: Shabbat 3:1-3).