All of the above. With two and a half hours on the train every day I read a crapload of books including (but not limited to) Scott Meyers' Effective series, Her Sutter's Exceptional series and Bjarne Stroustrups "The C++ Programming Language".
I also follow a number of websites such Herb Sutter's blog, Bjarne's webpage, isocpp, this site, AltDevBlog, stack overflow.
One of my favorite cpp videos is Herb's (my love for this guy is purely professional) Atomic Weapons.
Books mostly for me. Recently I decided to read books to see what the older books I started with missed. I've read or am reading (in order):
Accelerated C++
The Standard Library
Effective C++
More Effective C++
Effective STL
Practical C++ Programming
Data Structures and Algorithms
Thinking Like a Programmer (read it for fun)
Plan to get eventually:
Exceptional C++
More Exceptional C++
Exceptional C++ Style
C++ Templates
C++ Template Metaprogramming
I have The C++ Programming Language Special Edition too.
Books mainly.
ive been going through a book called "jumping into c++" because it is a fairly cheap ebook. i also got c++ for dummies because it was the only thing on sell at my local book store.
Books, lots of books. Just some of them are listed here:
http://www.cplusplus.com/articles/GLzyhbRD/
One day I will finish reading "The Art of Computer Programming".
I prefer a good book to scratting around the internet trying to piece various bits of knowledge together into one cohesive chunk (all the harder when you don't know the subject).
Edit:
And lots of playing around with code as you are reading.