Part-time job hunting? what to say when you appraoch manager?

i just turned 17 and am searching for a part-time job for weekends and after college. when i walk into a store, what is the best thing to say when i approach the manager to ask whether there are any vacancies available - this might sound like a silly question. you want to sound professional right? usually i walk in and say 'i was wondering if you have any part-time jobs available?' whats the best wording to use? peace