You can Both use a skullcap prop or the actual part of the figure you want to work on...Both will work. For the hair, I really prefer using a prop for the hairline details...It does a much more beautiful job!! But when you want to grow a moustache or facial hair it works better on the actual face,without a prop...that way if you make your figure 'talk'using mimic (let's say)...the hair will follow the movement...With a prop, you would have to keyframe and will would become a real pain;) So my advice is... Hair is better with a skullcap for the hairline... Facial hair(or any other body part)...better to grow directly on the figure (without a prop) This is not a rule though...this is only my opinion based on some experiences and lotz of try!!;)