Once you learn enough modeling to be useful, start working on a real design you're passionate about. Eventually you'll get to a point that you realize you need colors and materials, textures, fine detail you can't otherwise figure out, better lighting, animations and physics, particles, etc. Thats where you search for specific guides to tackle your specific problem.
When it comes to blender, I'd also highly recommend keeping up to date with the release notes and blogs about the development. Not only is the project continuously adding great new features, but the development notes they have are really useful for understanding why and how something would be used.