Unless Google and Bing stop changing their algorithms there is no one that can call themselves an expert. The best way to find someone who can do for you what you are looking for is to
ask your network for referrals , or if you don't have a network to ask the consultant for references. Everyone has an area they specialize in i.e. E-commerce, Blogs, Hyper-local ; so be sure to get someone with experience who uses whitehat techniques to improve your SERPs.