Women's and girl's hairstyles in the 1860's almost without exception begin with a straight, center part. The sides of the hair should be smooth either over or behind the ears. Women's hair should be gathered at the nape of the neck, and pinned up in some type of bun, roll, or braid. Bangs were not in fashion during the war wears. If you have bangs, you may find it helpful to use a type of hair pomade to incorporate your bangs smoothly into the rest of your hair. The best type of hair pins I have found are the 'U' shaped, metal or tortoise shell (modernly plastic) pins, as opposed to the usual bobby pins.
Some reenactresses with very thin or very short hair choose to use hair pieces to achieve a period look. (this is a period solution, by the by)
Girls and young women still in short skirts sometimes had short hair, but it was still in the same basic style - center part, and smooth sides. Other options for young girls include braids (one or two), and occasionally ringlets.
Hairnets were also sometimes worn by women - for more on this, and the 'snood' myth, see What Not to Wear.
