The first thing that you should do is prepare a business plan. In this market place landlords tend to be more skeptical about new start up businesses. If you have a decent business plan it will help make your concept easier to sell to the landlord as to why he should let you in his center.
You probably should hire an experienced commercial real estate agent in your area. They have the tools that you need to help you narrow down how much square footage you need, find locations, negotiate deals, and help determine if the site that you like will work with your city's zoning department or not.
You also need to have a good deal of cash saved up for your build out expense. I am not familiar with your area, but in the Washington DC area, landlords provide little money for retail build out. You need to have something set aside to put towards building out your space.
All of this is a start! I hope that you are successful in your endeavors.
Jul 9, 2009