What exactly should I do to find a job?

I'm 16 and a half. School's out for the summer, so i'm looking to work my typical 40 hour a week job, or a job in general. I'm going job hunting soon, and I mean really soon. I have a lot of places around here (the area is very commercialized) like Burger King, Mcdonalds, starbucks, dunkin donuts, wegmans, and local places. Now, I don't have any way to know if any of those areas are hiring, especially the local ones because they tend to not put out signs. What do I do? I've already asked BK for an application but that's when they had a sign out for help wanted. My main issue is if they don't have signs out and there's no way to tell if they have openings, can I just go in and ask for applications anyway? Thanks for your help.