1) Very important - get the design patented. That is very important you are going to have to tell lots of people about your new idea. Some of them may think, in the future, that it was there idea, others may just blatantly copy you.
2) Set up your company and decide upon a great name for it. When you describe your company, ensure that you company can expand it into other products and business areas.
3) Write your business plan, defining your business, financial and marketing strategy as well as your business structure. Approach your lenders for seed money/start up funds if required.
4) Decide upon your product name, your price points and your initial target market. Your price should be attractive enough so that a potential customer or retailer can afford to try out a new product, but high enough to ensure that you can make a profit.
5) Get some samples of your new product made up in several different designs and colors. Use different fabrics if appropriate. If you have to use an external manufacturer you may have to produce a minimum amount so produce the most cost effective number and design options. Ensure you get a non disclosure agreement (NDA). Each sample should have your company and product name on it either as a tag or stamped into it. This is to ensure easy product recognition when people take it away with them.
6) Go to an appropriate trade fair with your product and set up a stand. Have plenty of literature to hand out. You should be able to gauge interest here and hopefully take orders.
7) Approach potential retail companies with your success story. Start with the smaller ones and work your way up.
8) If you get a reasonable response/orders then off to the bank with a loan request so that you can start your business in earnest.
If you wish to start slower or don't have the capital to do the trade show - then start at flea markets, product parties and mall karts and work your way up.