1. Most part of the face is cropped out..this might be too extreme for some people but then again, there's no limit to creativity, right? Careful though..not to be too extreme until it's impossible to identify who the person is.
2. Visible shoulder with cut-out upper-head with a fair amount of background to the left or right.
3. As corny as this may sound..I'll have to say, focus on the emotion, guys! Happy, love...whatever.
4. Fair amount of background with smaller focus image positioned to the left or right because center is boring. Make the icons tell you the story. It's better that way.
5. Cut through the nose and discard the upper-head. Looks a little bit weird or funny depends on your point of view, but I still like it.
6. Place the focus subject a little bit to the left or right instead of center.
7. Discard the upper-head and place the image to the left or right. Be sure to cut a little closer to the eyebrows to avoid the subject looking bald.
The tutorials below might give you an idea on how to nicely cropped your image:
1. How to achieve a good image position
2. Might wanna read about this aspect ratio thingy
3. More Cropping Tips