to run your own business nothing is really required (its your show), but experience in retail sure helps, and having good customer relations, and managment experience is a plus, but if really worried about school, depending on the aspects, Business Management, Financing, etc are great way to learn the most about running a place of business...
As far as owning/running your own place goes, location is key, especially today with competitors usually popping up all over the place, but like any business no matter the size its a gamble, and the first year is usually really tough, but after that if you can struggle through it rest should be a breeze. I have some family members who owned and ran their own store of various sorts, and I am currently at the management level in my life, and have worked with various retail stores, as well as the private sector. There is only one way to find out if you can do it though (1 I hope to find out myself someday soon as well) TRY IT... you can't make it if you don;t, and you won't know unless you do.... is the risk worth it to you?