Coding Style

Line Formatting

No tab characters (configure your editor to insert spaces instead)
Indentation in steps of 2
Opening braces have their own line, aligned with the previous line; corresponding closing braces are placed on their own lines, at the same character position as the opening brace.
For function definitions, return types appear on their own line, such that the function name is first in its line.

Naming

ALL_UPPERCASE_NAMES are reserved for preprocessor macros.
Use CamelCase (uppercase letters inside words) to indicate word boundaries.
Class names and namespaces begin with uppercase letters: MyNameSpace, TheClass.
Local variables and function arguments begin with lowercase letters.
Accessor functions use Set/Get or directly the name of the property. Setter functions should return a non-const reference to the data object itself rather than void.

Name prefixes

Prefixes should carry information about the scope and usage of a variable but not its type.

m for class data members
s for static class members and static variables
g for global variables
c for constants
p for pointers
fp for function pointers
in for function input arguments
out for function output arguments
io for function arguments used for input and output

Pointers, References, Stack and Heap, Memory allocation, Control flow

Always use the narrowest possible scope for a name to avoid side effects.
Always initialize variables (at declaration resp. constructor).
Allocate from the stack rather than the heap unless there is a good reason to use the new operator. This avoids memory leaks.
Use references rather than pointers wherever possible.
Use STL containers rather than allocating arrays with new[]. This eliminates a number of possible errors (initialization, allocation, deallocation).
Avoid goto, break outside switch-case blocks, and multiple return statements.

Example Function

void
MyClass::MyFunction( const int inMyInput, int& outMyOutput )
{
  outMyOutput = 10;
  for( int i = 0; i < inMyInput; ++i )
  {
    int k = 4;
    while( --k > 0 )
      outMyOutput -= k;
  }
}