On Erev Sukkot, one should not donate blood or undergo any procedures or tests involving blood loss. [This does not apply in cases of great need, and certainly not when it is Pikuach Nefesh.]
On Erev Sukkot, one should not eat (a meal) in the Sukkah.
The Mitzvah of V’Samachta B’Chagecha entails eating meat, wine and delicacies; providing new clothing or jewelry for one’s wife according to his means; and giving sweets to the children. These should be arranged in advance.
One may not launder on Chol Hamoed. Therefore, any laundry should be tended to before Sukkot.
When necessary, one should take a haircut in honor of Sukkot.
Nails should be trimmed in honor of Chag. [Another reason to tend to them on Erev Sukkot is because they otherwise cannot be trimmed on Chol Hamoed.]
Some immerse in a Mikvah after Chatzot (12:26pm).
Chag is an especially appropriate time for guests. This is emphasized on Sukkot, because the function of a Sukkah is to unite all of Klal Yisrael. Additionally, hosting guests is especially connected to the Ushpizin.
It is forbidden to eat a proper meal of bread once the tenth Halachic hour of the day begins (3:22pm), in order to properly enjoy the meal of the first night. However, one may snack in small quantities.
Even though all meals will be eaten in the Sukkah, some have the custom to place a tablecloth on the table in the house, in honor of Chag and others specifically do not, to remind them to eat in the Sukkah.
One should give Tzedakah on Erev Sukkot for the Chag. We all have the obligation to make sure that the Chag requirements of the needy be met, including a set of Daled Minim and a Sukkah.
Candle-lighting (Monday night) is at 5:41pm. The Brachot are L’Hadlik Ner Shel Yom Tov and Shehecheyanu.
The candles are lit in the Sukkah and kept there until the end of the meal. At the very least, they should be lit in the Sukkah and moved only after some time has elapsed and some benefit has been derived. If even this is not feasible or safe, the candles may be lit indoors, preferably in a place where they can be seen from the Sukkah, and one should ensure that practical benefit is derived from the candles after Chag begins. If possible, the candles should be brought back to the Sukkah for the Chag meal.
If eating out, one should ensure that practical benefit is derived from the candles after Chag begins.
Since it is Chag, if one neglected to light at the proper time, one may – and should – light candles on Chag itself, from a pre-existing flame.
When a man is required to light candles, he does not recite Shehecheyanu, as he will be doing so in Kiddush. [Therefore, it is best that he lights candles right before Kiddush, so that his Shehecheyanu is linked to both.]
