C++ class header files organization

Question

What are the C++ coding and file organization guidelines you suggest for people who have to deal with lots of interdependent classes spread over several source and header fi

Answer 1

Tom's answer is an excellent one!

Only thing I'd add is to never have "using declarations" in header files. They should only be allowed in implementation files, e.g. foo.cpp.

The logic for this is well described in the excellent book "Accelerated C++" (Amazon link - sanitised for script kiddie link nazis)