If you're trying to hire an eCommerce development agency, your best bet is to look for those that specialize in eCommerce. You'll also want to inquire about the profiles of developers, will the company provide support after the website is live? Do they have a fixed fee system or do they charge by project-based and how many hours? You want your new website developer to be as upfront as possible- if you feel they are being secretive, find one that reciprocates honesty.