Where to go next...

So, I've been practicing HTML and CSS for a few months now and have become familiar with most of the language. But still, I don't really understand how the pros start out on a site and in which order they do what, how they go about making things like sidebars step by step, etc. I really wanna step my game up to the next level, but I'm at an awkward position. I've found that the only videos I haven't seen are the ones that are for beginners and tell me things I already know. Do you think it'd be beneficial to start learning something like Bootstrap/Foundation to see common formatting and methods for doing those practical things that are just too specific to include in a treehouse tutorial? Where do I go from here??????