If you are new to e-commerce, I'd suggest starting with Amazon and eBay as Jhon Albert pointed out. I'd advise you to start by observing the trading on such sites. This is the best you can do to help yourself. Look at how your competitors are doing in the children's clothing business. Look at what people order most often and what tricks manufacturers use to attract customers. I'm sure that soon you will find some feature that will distinguish your product from others. For the same reason, I like to watch how embroidery near me develops. They conquer the quality and originality of their products.