Largest you can dominate

Identify one under-served niche audience that you can astonish. 

The secret to being best in the world is to make the "world" smaller. 

Pick the "largest" audience that you can dominate. 

This is an ideal approach for old, fallen, tired, niche, small and untested products. Better to be the 1st choice of a small audience than the 3rd or 4th choice of a large, crowded audience. If it is a win in the niche, then build it out. 

(TY: Seth Godin and unknown)