I am not sure what exactly you mean by improving your ecommerce website. There are various aspect that needs to cater while working on ecommerce website:
- Onsite structure (landing pages, search facility, easy navigation, information organization and overall usability).
- Website speed (development of website and information rendering)
- Search Engine Visibility (here it is very important to make your website search engine friendly - refer Google webmaster guideline for more help).
- Social Media and Paid Marketing
- Shopping engine submission and monetizing
- Affiliate marketing
Its been 6 years i have been involved in eCommerce product marketing and i am sure given point will help you to find the right person for your website.
all the best