When the month of Av arrives, we reduce the amount of joy.
Among the things which are avoided during these nine days (in addition to the activities avoided during the whole three weeks) are eating meat and drinking wine, swimming, bathing, doing laundry, wearing freshly washed clothes, and sewing.
It is recommended to prepare before the Nine Days and make sure to wear, albeit for a short period of time all shirts, pants, dresses, skirts, etc., that one plans on wearing during the nine days.
One should not do any construction during these days unless it is for actual dwelling purposes, or for the public need. One may build a shul or Yeshiva during these days.
One should not paint his home during these days.
During the nine days and until midday of the tenth of Av, one is not permitted to eat meat or drink wine, except on Shabbos. If the shalosh Suedos extends itself into the night and they have not yet davened Maariv, they are permitted to eat meat during that time.
One may also not eat food that was cooked with meat, even if he is not eating the meat. For example chicken soup, where all the chicken has been removed may not be eaten during the nine days.
One who is ill and needs to eat meat is permitted to do so.
Many people avoid making Havdalah on Shabbos Chazon over wine and instead use beer. However, others do make it over wine and it appears that one is permitted to drink the Havdalah wine himself, while others give it to children to drink.