Looking for someone to help tweak our facebook campaigns and optimise

We are running some facebook advertising and I need someone to help look in on the ads and optimise them. Give me some suggestions on how to improve results etc. Our main goal is to drive people over to our landing page on our website and get them signing up to our subscription boxes. We have in house designers to make new ad artwork and are happy to have the person make changes themselves or direct us on the necessary changes that need to be made. So ideally someone that can look in every few days on the ad's and offer some insights. We'd ideally like to work with a person long term and pay them a biweekly fee for their help. Thanks