If you're going shopping, what makes a good label? It just has to be something that better enables you to make a decision- so the main thing is having information about the "product" (clan).
A lot of clan pages do go somewhere in that direction- for example, y'all say "diplomacy is the preferred game mode for us" or something like that in your page. But that's like trying to pick between Cheerios and Special K after looking at the box and just reading "HEALTHY" or something stupid like that.
There's two steps to making an effective clan: differentiate, then outdo. You want to make both clear on your page. What makes your clan different from most clans? What makes your clan better than any similar clan?