A style that is slightly longer than the chin, shaped and softened around the edges, flatters a square face. This gives the illusion of length to your face. Hair should not be cut shorter than, or in line with the chin, as this would make the face appear squarer. Avoid center partings and straight bangs. For someone with a heart shaped face balance between the forehead and chin is very important. Layered hair shaped along the face near the chin, thick at the bottom and with layered bangs will provide fullness where needed. Straight styles, which cling to the face, would accentuate the narrow jaw line and is not recommended.
Women have some facial features which will look better with short, cropped hair. Always wearing your hair in its natural way or wearing it in straight black hair? Why don't you try having your hair short and cropped?