Social media account development

I have a membership website and need the social media pages developing, including youtube, twitter, facebook and instagram. They are already up and running but i need someone to take control of these, develop them to increase exposure of the website. Ideally to use all possible ways of exposing the website on the internet. This will be for an initial period but may become an ongoing project depending on the initial results. In replies, please state clearly what your plan would be and on what timescale.