You need a tax payer identification number. You need a business license. You need a location. You need inventory. You need to know your customer demographic and how to market to them.
The most important thing to remember when opening a retail store is finding a supplier who can meet your needs. What I mean by this is finding someone who is willing to sale you wholesale merchandise at a reasonable price. So you have a "nice" net worth left over at the end of the week.
A thorough understanding of the market will be useful. Get the required licence etc. for your retail store. The location of the store is important and select a place where you think the business will flourish. During the starting point itself, decide your selling strategies and how you are going to deal with your taxes.
Open a store requires financing, a commercial space (leased or purchased), stock, and employees. The most difficult part of the equation is obtaining financing. Having a well-written business plan, along with good credit, is usually necessary.
First find a location, for a retail store it's good to have a stand alone operation. Identify what you are going to sell and to who you want to sell it too. Then you can determine pricing and advertisement.