SOme quick ones:
-end with a quad @ the corner of the mouth and the inside of the ear
-extrude an edge inward for the mouth at the very least
- the eyes are to close to the center
- nose is to pointy

My advice is download as much refernce photos of a tiger you can find even better is to have some bookmarks to some video's since a photo is only one moment and you could be working of some odd expression I prefer footage with headturns those are the best