Read The C++ Programming Language by Stroustrup cover to cover, and then read it again and again. Then, as you work with C++ programs, keep referring back to that book to remind yourself of the details of various topics.
It is, by far, the best book on C++ available, and since the author invented C++, you will get a good sense of the intentions and rationales of the various language features.
Once you have mastered the contents of that book, the next step is to familiarise yourself with the C++ 03 and the upcoming 0x standards. Reading a language standard can be hard, but once you get used to the style, standards are invaluable resources.
It is very important to be familiar with the authoritative resources and not get lead astray with possibly incorrect or out-dated information out on the web. I've seen programmers make really dumb mistakes because they just searched on Google to find out how some language feature works.