I prefer not to insult my models by improving their features. I think that is what makes them individual. However, there are ways to draw the features that they would be self consious about in a way that does not accent the problem feature. Lighting, contrast and positioning all come in to play when you are trying to give the model a good pose. I rather think it is best to be as accurate as possible, but without exxagerating the problem feature. Better to error on the side of flattery.
My grandfather who was my teacher was great at portraits from photos, but not from life. I remember one occasion when he was hired to draw at a formal dance party, and I came along as his assistant. (I was about 12 years old.) A beautiful lady sat down for a portrait. My grandfather had a bad way of exxagerating the muscles of the neck, and the bulbs of the nose, which he did on this elegant lady. It was the first, last and only portrait he drew the whole night!
