97:6 On Rosh Chodesh, we are forbidden to fast or to give a eulogy. Likewise, the funeral prayer Tzidduk HaDin is not recited.
97:7 We are required to sanctify the moon ("kiddush levana") every month. (Women are not obligated, since it is a positive time-bound mitzvah - Mishnah Brurah 426:1.) One only sanctifies the moon when it is definitely night, when its light can be seen on the ground, and we are able to benefit from its light. If the moon is obscured by a cloud, we don't sanctify it unless the cloud is thin and wispy (so that the moon and its light may still be seen through the cloud - MB 426:3). If one started to recite the blessing and the moon became obscured by a cloud, he finishes the bracha. If one thinks that he can't finish the bracha before the moon becomes obscured, he is not permitted to start.