You've been successfully selling your wares on eBay for a while, and you're seeing a greater demand for your products. Now that you've gotten a taste of success, you're hooked--and you want more. So how do you take your business on eBay to the next level? We asked Susan Phillips, vice president of marketing at eBay, for some tips.

First, examine how you're running your business, and look for places you might be more efficient, suggests Phillips. "Are there tools you're not using that could help you be more productive?" she asks. "Or [perhaps] you've gotten to a point where you started with a very basic tool and you need to upgrade." The listing tools offered by eBay, for instance, can help you create multiple listings at once, which will save you a lot of time. Turbo Lister, in particular, is designed to help medium- to high-volume sellers.

Next, look at your fulfillment side--packing and shipping items can be a huge time drain on your growing enterprise. "eBay has relationships with organizations like UPS and the U.S. Postal Service that allow sellers to calculate the shipping cost upfront and print shipping labels at home--there are even eBay/USPS co-branded boxes sellers can get for free," says Phillips. "These little timesavers make a big difference when you're shipping a lot of items."

Once you get your back-office operations at optimum efficiency, you need to start thinking about inventory management--tracking the items you're selling and how much profit you're making. Inventory management also helps you decipher when you need new sources of merchandise for your growing business. Say you've sold out of your original inventory or you've exhausted your original supply line. There are many different ways to find products, says Phillips, from grass-roots-type tactics--such as canvassing local estate sales, garage sales and outlet malls for low-cost inventory--to asking friends, relatives and neighbors if they have anything they'd like you to sell.

Or you can take a more formal step and become part of eBay's Trading Assistant Program. When you do, you can list your services on eBay's Trading Assistant Directory, where people with products they want help selling can find you, says Phillips. If you want to buy larger lots of items, you can check out eBay's wholesale section, or try the Reseller Marketplace. This is a venue for sellers to liquidate returned, refurbished or otherwise excess inventory in bulk lots to eBay Power-Sellers for resale on eBay and through other channels.

Your overall growth strategy will depend largely on your personal goals for your business, says Phillips. Do you want it to be a part-time gig or a full-time sole proprietorship? Or do you envision opening a complete online store, selling hundreds of products and requiring staff? When you're constantly asking friends and family to help you fulfill orders, it's a good sign you're ready to hire help, Phillips says.

Finally, there's an enormous number of resources for sellers on eBay to help you grow. From the listing programs to online forums to real-life eBay educational seminars in your community, you can find a way to build a larger eBay enterprise. "Be as disciplined as possible--there are ways to make [operations] a little more efficient," says Phillips. "And by doing so, you'll save yourself enough time to grow your business that much further."