• One should not fast on Rosh Chodesh, even if the fast is intended for just a few hours 1.
• Although there is no obligation to wash and eat a meal in honor of Rosh Chodesh, one should endeavor to increase in one's eating on Rosh Chodesh in honor of this day, and even to include bread during the meal2.
• One should not have his or her hair cut on Rosh Chodesh, even if Rosh Chodesh comes out on Friday and he or she wants to take a haircut in honor of the Shabbat3.
• One should also avoid cutting one's nails on Rosh Chodesh4.
• If a child turns three years old on Rosh Chodesh, the Opsherenish (cutting of the hair at the age of three) should take place right after Rosh Chodesh and not on the day itself5.
Grace After Meals
• In grace after meals, we add the Yaale V'Yovo - "May there ascend..." in the third blessing (for the text of the Grace After Meals click here). If one forgets to say the Yaale V'yovo and realizes his error before saying G-d's name at the end of U'vnei Yerusholayim - "And rebuild Jerusalem...," he can still say the Yaale V'yovo. If however he had already said G-d's name, he concludes the blessing and then adds these words:
Transliteration: Baruch A-to Ado-Noi Elo-hei-nu Me-lech Ha-o-lom She-na-san Ro-shei Cha-do-shim le-a-mo Yis-ro-el le-Zi-ko-ron.
Translation: Blessed are You, L-rd our G-d, King of the universe, who has given the days of Rosh Chodesh to His people Israel for remembrance.
• If he had already said the first word of the fourth blessing, he continues with the grace and does not repeat it.
The Prayers
• On Rosh Chodesh we recite the "half Hallel." The Chazan, cantor, should say the blessing at the beginning and the end of Hallel on Rosh chodesh and thereby exempt all the congregants, and the congregants should answer Amen and thus be included within the blessing6.
• We insert Yaale V'yovo in the Amidah of Shacharit, Mincha and Maariv of Rosh Chodesh. It is inserted in the blessing of Retzei. If one inadvertently omitted Yaale VeYovo and realized his error before pronouncing G-d's name at the end of the blessing - Hamachzir Shecinoto Letzion, he returns to Yaale V'Yovo and says it.
• If however he realized his error after pronouncing G-d's name, the following rules apply for Shacharit and Mincha:
A) If he realized the error right after saying G-d's name, he adds the words Lamdeini Chukecha and returns to Yaale V'Yovo7.
B) If he already started HaMachazir, but did not start Modim, he can say Yaale V'yovo right before Modim.
C) If he already started Modim, and realized his omission before completing the Yihiyu LeRatzon at the end of Elokei Netzor, he returns to Retzei and continues from there.
D) If he already said the Yihiyu Lerotzon before Oseh Shalom, even though he did not take his three steps backward, he must return to the beginning of the Amidah.
• During Maariv, however, once he has passed G-d's name in the blessing of HaMachzir, he cannot avail himself of any of the options mentioned above. He simply finishes the amidah and does not repeat it.
