In general, civilian clothing and accoutrements must adhere to the same standards as for military gear. Fabric should be 100% linen or wool, or cotton or silk in some cases. Any exposed stitching should be done by hand. The following descriptions are very rudimentary, and you are strongly urged to do some research, especially on decoration and jewelry, before making your clothing.
The tunica is the basic woman's garment, similar to a man's tunic but longer. It is 26" to 40"+ wide and reaches to the ankles when belted. It is generally sleeveless, and the neckline is a horizontal slit made by leaving part of the top seam unsewn. The top can also be held with brooches instead of being sewn. When worn as an undergarment the tunica is best made of fine white linen, but otherwise can be colored linen or wool.
The stola is the distinctive garment of a married Roman woman, but it is unclear exactly how it differed from the tunica. Apparently it was pleated vertically and pinned or buttoned along the top edge. It should be quite wide, and long enough to cover the tunica even when belted up. There can be one belt at the waist, with the fabric bloused over it, or a second belt under the bust as well.
Another option is the Greek peplos. It is made of 2 large rectangles, approximately 45" wide by at least 60" high (or a single panel of that total size, with the top edge folded down and the folded edges pinned together at the shoulders. If the sides are sewn closed, no armhole is left; the arms go through the "top" slit on either side of the neck opening. The overhanging fabric can either end above the waist to show the material which is bloused over the waistbelt, or the garment can be made tall enough for the overhang to extend almost to the knees.
The palla is a large rectangular wrap, at least 5' by 9'. It is roughly equivalent to a man's toga, but was always worn by a decent woman in public, and could be put on in a number of ways. Various wraps or cloaks (see the page on men's civilian clothing) were also worn.
The strophium is the Roman brassiere. It is a band of soft linen 6" to 8" wide (or a folded wider strip), long enough to go around the body at least twice. It can be worn in several ways, for example placing the center of the band at the back and crossing the ends in front to support the breasts, then wrapping the ends around and tucking them in again. Evidence is scarce, however, and pins or ties may have been used.
While the tunica often served as an undergarment, there are also references to the supparum, subucula, and (for matrons) indusium, which may all be slip-like garments, hanging from the waist. Dancing girls are shown wearing "bikini briefs", and a pair of woman's panties made of leather have been found, but it is not known if these were common items of apparel.
Hair styles were amazingly varied. While upper-class women favored elaborate arrangements of curls and ties, simpler hairdos involved coiled braids or a bun at the back. Wigs were used, and those made with red or blond hair were desireably exotic. Traditionally, girls and women tied their hair back with thin woolen bands called vittae, which were considered spiritual protection. Mature Roman women would always cover their heads with a veil or part of the palla when out in public.