The custom is to appoint a righteous, benevolent, Torah-oriented person to blow the shofar for the community, but it should not become a matter of contention (MB 585:3). If possible, it is better to place the shofar on the right side of the mouth. It is also customary for the wider opening of the shofar to face upward, as it is written, “God ascends with a blast; the Lord, with the sound of a shofar” (Tehilim 47:6).
In the past, when people recited the prayers by heart, the custom was to make sure that the ḥazan for Musaf would not blow the shofar during the Amida, lest he become confused and lose his place. Nowadays, though, when people pray from maḥzorim, we are not concerned about this issue, so the ḥazan may blow the shofar as well (SA 585:4; MB ad loc. 14).
The shofar-blowing is not divided among several people. Rather, one person blows all the shofar blasts, as “one who begins a mitzva should be encouraged to complete it” (Rema 585:4). However, where dividing it up is an established custom, the congregation may continue doing so, as it shows how much people love the mitzva (MB ad loc. 17).
Since the berakha recited on the blasts before Musaf also covers the blasts during Musaf, one must make sure not to talk until all the blasts have been sounded (SA 592:3).
In many places, the rabbi or another Torah scholar quietly prompts the shofar-blower, telling him which blast to blow, to make sure that he does not get confused (Rema 585:4). The custom is to prompt even for the first blast. Although there is no concern for mistakes, some maintain that the prompt also helps focus (Shlah; see SHT 585:31).
One must hear every blast from its beginning to its end. If someone heard only part of a blast, he has not fulfilled his obligation. Therefore, the congregation must be totally silent during the shofar-blowing. One who needs to cough should suppress it until after the blasts (MB 587:16).
Ashkenazic custom is to conclude the set of the first thirty blasts as well as the last of the hundred blasts with an extended blast, called a “teki’a gedola.” It alludes to our great and never-ending faith. Sephardic custom is to blow an extended teru’a at the end of the service, to confound the satan (SA 596:1). The subtle message is that while we may still experience crises and “breaks,” they are ultimately transformed for the better.
If the shofar-blower feels weak and is unable to continue, someone should take over from him. If the substitute heard the earlier berakhot, he does not need to recite new berakhot, as he has already fulfilled the obligation with the berakhot of the first shofar-blower (SA 585:3).
Many shofar-blowers take two shofarot with them, so if they have difficulty blowing one, they can switch to the second. In such a case, a new berakha need not be recited, since the original berakha applied to both. Be-di’avad, even if someone started out with only one shofar and was given a different one because he had difficulty blowing the first, he need not recite another berakha (MB 585:4).
One may rinse the shofar with water, or even wine, vinegar, or arak, to improve its sound quality. This is not considered a weekday activity that is forbidden on a holiday (SA 586:23).
Some people, following Arizal and Shlah, offer various confessions and prayers after every three sets of shofar blasts. Where a congregation follows this custom, the shofar-blower stops blowing in order to accommodate them. However, many poskim rule that no prayers should be inserted during the thirty blasts. Both practices can be justified. In contrast, it is never permitted to insert a prayer between the recitation of the berakha and the beginning of the teki’ot (MB 592:12; SHT ad loc. 15).
. It is preferable to pray with a minyan where he will definitely fulfill the obligation to hear the shofar, even though the prayers there are not particularly dignified and it will be difficult to concentrate, than to go where the prayers are dignified and he will have proper focus, but the shofar-blower is so inept that it is not certain that he will fulfill the mitzva. This is because shofar is a Torah obligation, while prayer is a rabbinic one (Rosh Ha-shana 34a; SA 595:1). The same applies to the second day, since the basis of the obligation to hear the shofar is from the Torah.