How can I make sure my ebay listing is found when there are over 10,000 similar products?

I am fairly new to eBay and am hoping to use it as a source of extra income however, I need to know how I can make sure that my listings are found when there are several thousand similar products (e.g. iPhone/ iPod accessories, cases, screen protectors). Also, what can I do to ensure my listings appear professional? Thanks in advance!