The next steps for skinning effectively are getting your development environment configured and building the scaffolding for a theme product. It is also important to learn some of the jargon associated with Plone 3 development so that you can understand the development environment and how to use it.
Prior to Plone 3, setting up Plone was fairly straightforward: you installed Plone and dropped all of your Plone add-on products into a Products
directory. Making modifications meant that you simply edited a template and your changes showed instantly. While that sounds simple (and for themers, it was), it was not flexible or repeatable, and resulted in the development of monolithic products that were difficult to distribute or reuse and could only be used in the context of Plone.
Since Plone 3, the development environment has moved toward a more pluggable "egg-based" environment. Eggs are a way to package and distribute Python packages...