Hallel
If you are saying Hallel without a minyan, say the berachos at the beginning and end. When saying the berachah at the end of Hallel, the word al is omitted.
Many are accustomed to saying these berachos even when saying Hallel with a minyan. If doing so, say the berachos before or together with the chazzan, and do not answer amen on the chazzan’s berachah.
Repeat the possuk of Hodu after each of the three pessukim of Yomar na (even when saying Hallel without a minyan).
With regard to interrupting for devarim shebikdushah, Hallel shares the laws of birchos krias shema. (To elaborate: With Kaddish, you may interrupt for Yehei Shmei Rabba and the amen of da’amiran be’alma. With Kedushah, you may interrupt for Kadosh, Boruch, and Yimloch. With Modim, you may say the words Modim anachnu lach. You may interrupt for Borchu and for the amen of Hakel hakadosh, Shomei’a tefillah and birchos hatorah.)
Bentching
The one leading the bentching raises his voice when saying the words zachreinu Hashem Elokeinu bo letovah, u’fakdeinu vo levrachah, vehoshi’einu vo lechaim tovim, and those listening answer amen after each phrase. However, if they are in the middle of bentching as well, they may only answer if they are between berachos.
If you forgot to say Yaaleh Viyavo and remembered after saying Hashem’s name at the end of the berachah but before starting the berachah of Hatov Vehameitiv, say the added paragraph for Rosh Chodesh printed in the bentcher or siddur. If you remembered after starting that berachah, do not go back.
