The ratio of upper to lower lip should be 1:1.6 & the upper lip should stick out slightly further than the bottom lip. Nowadays the trend, however, is to have more similarity in the sizes of the upper and lower lips. There is also a line in the profile view from the nose tip to chin where ‘perfect distances’ from the upper & lower lips to the line are a sign of beauty. It is not just a case of putting filler in the lips; an assessment of your profile, lip size and facial proportions are imperative to give a natural look.
As we age our facial skeleton decreases in size as well as our lips. Assessment must also take this into account.