The only configuration necessary to start using plugins is to add the following T4 navigation tags to your header and footer in your page layout (template).
These navigation tags belong to the "Plugins" group but can be used cross channel because they are not pulling in any channel specific information.
You'll then need to enable the plugin for your section or branch so your users can use it. You'll do this by going to the Section > Content Types and enabling the plugin you want your users to be able to use. Available plugins are added to the "Plugins Users" group. (Enabling plugins on a page from the "Plugins" group will not work, because only Web Services staff are in that group.)
From there your users who are in the Plugins User group will be able to use the plugin.
As outlined below, plugins are namespaced with a wrapping <div class="plugin-pluginName"></div> and include minimal styles. This way website owners should be able to style each plugin to match their website easily by utilizing that opening "plugin-pluginName" class.