The Ben Ish Chai (Rabbi Yosef Chaim of Baghdad, 1835-1909) writes that when one begins reciting Havdalah, he should hold the cup of wine in his right hand and the Besamim (spices) in his left hand until he reaches the Beracha over the Besamim, at which point he should transfer the cup to his left hand and take the Besamim in his right hand. Rather than leaving the Besamim on the table until the recitation of the Beracha over the Besamim, one should hold the Besamim in his left hand from the beginning of Havdalah.
The cup used for Havdalah must be rinsed both the interior and exterior prior to Havdalah, to make sure it is clean.
Optimally, one should drink a full Revi'it or slightly more than 3 oz. of the Havdalah wine. Nevertheless, one fulfills his obligation even if he drinks less than this amount, provided that he drinks at least a majority of Revi'it, or approximately 1.6 oz.
When filling the cup of wine for Havdalah, one should have it overflow to signify our hopes for a week of abundant blessing. Some people do not have it overflow initially and instead shake the cup as they recite the Beracha of "Borei Peri Hagefen" so that some wine spills. This practice is improper for several reasons, one of them being the issue of Hefsek (an unwarranted interruption in the middle of a Beracha). One should instead have the cup overflow the top when he fills it with wine before reciting Havdalah.
Several customs exist involving dipping one's fingers in the wine after Havdalah; all these customs serve as an expression of Chibuv Mitzvah love for the Mitzvah. Some people dip their fingers in the wine and then rub it on their eyes. Rabbi Chayim Palachi (Izmir, Turkey, 19th century) would rub the wine on his eyes and recite the Pasuk (Tehillim 19:9), "Mitzvaht Hashem Bara Me'irat Enayim" ("The instruction of Hashem is pure, enlightening the eyes"). Others place the wine on their neck, at the bone underneath the skull, from which the resurrection will occur. Yet another practice is to place the wine in one's pockets, whereas others have the custom to place the wine on wounds. All these customs are expressions of our love for the Mitzvah.
The Arizal (Rabbi Yitzchak Luria, legendary Kabbalist, Egypt-Tzefat, 16th century) maintained that for Besamim one should use three Hadasim (myrtle branches, as we use on Succot), and they should conform to the specifications required for the Hadasim used on Succot. After Havdalah, one should not discard the Hadasim used for Besamim; he should rather put them aside until they wilt, at which point they are no longer suitable for the Beracha and may thus be discarded. Some people have the practice of leaving them until Erev Pesach and burning them with the Chametz.
Some people have the practice of smelling the Havdalah candle, also as an expression of Chibuv Mitzvahh.
