Normally for lip augmentation I don't use a full 1 cc unless the patient is really looking for volume to plump the lips up.  In most instances, patients are concerned about the vertical upper lip lines and by injecting dermal fillers such as Restylane along the border between the pink part of the lip and the flesh-colored part (vermillion-cutaneous junction), you accomplish a smoothing of the lower quarter inch of the vertical line as well as give the upper lip more definition.  Some women like the upper and lower lips to have the same amount of fullness, other women like the lower lip to be 50% larger than the upper lip.  For this reason it's important to discuss with your doctor would goal you're trying to achieve.