Qualifications
You need to be willing to stand on your feet all day carrying heavy bags back and forth from the room to the hotel lobby. And you need to be able to do it with sparkling personality.
Ability and attitude are the two main requirements for this gig. If you don't have one of those can-do attitudes, better whip one up quick.
Whiners, lazy people, and loners need not apply.
You also should probably have a fairly decent sense of direction and solid knowledge of local restaurants, tourist attractions, and nightlife, as many guests will be asking for your advice. The better the directions and suggestions, the bigger your tip will be.