Read Literate Programs
Explore code bases that use a literate programming approach (as introduced by D. Knuth), it will help greatly.
Read Good Example Projects
Some other pages are very well documented and can be of good help to see either good practices, bad practices, and practices that are good in constrained environments but may make your code hard to read and maintain. By the way, you mention jQuery as something you don't want to use... but reading jQuery's source might also be a good idea, as well as the source of other frameworks.
Have a go at the following ones to see what I mean (in no particular order here):
You may want to look for a few blogs to follow for yourself.
I don't really want to point out anyone in particular. Tastes vary, both in terms of writing style, coding style and programming paradigms. That being said, learning from people using techniques you dislike is also very enlightening.
Here are still a few for pointers:
Experiment with Different Frameworks
And this, extensively: read the code, follow the tutorials, do benchmarks.
Here are some for a start (in alphabetical order):
Sure, they will hide some of the complexity for you. So be sure to understand what's happening under the hood.
Have a look at what JS can do for you in other environments - not only on the client side - as well, for instance with node.js.
Teach yourself about the Interpreters
They run your stuff, so you better know what they can and cannot do, and how it impacts your websites rendering and performance.
Speaking of Benchmarks...
If you need to test this (and take the habit of doing so), meet your new friends:
Have a browse on the above to see great examples people published.
The ECMAScript standard exists for a reason. Read it, even if it is (or appears) unreadable. ECMA-262, 5th edition, is your bible for the stuff under the hood reference.
Still some complements to the standard might help...
Lurk on StackOverflow