Seeking Advice on Creating a Client Care Plan and Pricing Structure

Hey yall - I posted about this before with little response so I'll try again. Ive had a bunch of clients ask me for some sort of care package. A lot of companies I work with don't have an "webmasters" or anyone to help with design assets or make small changes to their site as marketing initiatives change. Think its time to set something official up and was wondering if anyone has ever set up a care plan and what kind of charging structure they have. Thanks!