Barbra Streisand is famous for knowing which lighting is best for flattering her features. This gives her a reputation of being 'difficult' and 'high-maintenance', but it's really just her being professional, experienced and watching out for her best interests.
It's lovely to be relaxed whilst in front of the camera and not 'stiff'. Feel comfortable with having your picture taken. I love action photographs and unposed 'shots'. However, when it comes to having to 'pose',
this picture illustrates my own usual angle. From experience, it works well. I came across it by accident. My friends like to imitate my "pose" and ask me to do it, so I guess it's a kind of 'signature'. Everybody is different and has different attributes and features to illuminate. If you don't know what works best for yourself, try copying pictures from magazines whilst standing in front of a mirror.