Festivity of Rosh Chodesh
This is the approved revision of this page, as well as being the most recent.
Fasting on Rosh Chodesh
- It's forbidden to fast on Rosh Chodesh. 
- One should add on to one's meal with at least one food more than usual. 
- One can fulfill this with any type of special food, however, it's praiseworthy to do so with bread and make Birkat HaMazon (with Yaaleh VeYavo). 
- One fulfills one's obligation with the meal of the day and it's not necessary to have a meal also at night. 
- Some have the minhag to fast on Erev Rosh Chodesh (the day before Rosh Chodesh) and even those who don't fast should do teshuva on this day since it's the last of the month (similar to Erev Rosh Hashana). 
Working on Rosh Chodesh
- It's permissible to do work on Rosh Chodesh. In some places the minhag is for women not to work on Rosh Chodesh and it's a praiseworthy minhag. 
Cutting Hair and Nails on Rosh Chodesh
- There is an Ashkenazic minhag not to cut one's hair, shave, or cut one's nails on Rosh Chodesh even if it falls out on Friday. Sephardim aren't concerned for this.
- Shulchan Aruch 418:1
- Shulchan Aruch 419:1, Mishna Brurah 419:2
- Mishna Brurah 419:1. Kaf Hachaim 419:2 quotes the Rabbenu Yahonatan who holds that there's an obligation to have a bread meal on a Rosh Chodesh and a Yareh Shamayim would be strict for him. He concludes that it is a nice practice to make hamotzei with two loaves of bread. Yalkut Yosef 418:8 writes that someone who has a bread meal is praiseworthy.
- Mishna Brurah 419:2
- Mishna Brurah 417:4
- Shulchan Aruch 417:1
- Mishna Brurah 260:7 writes that there is a minhag to be strict for Rabbi Yehuda Hachasid's will not to cut one's hair or nails on Rosh Chodesh even if it is a Friday.
- Yalkut Yosef 260:2