Most is taken from Ulrich Breymann: „C++ Einführung und professionelle Programmierung“ which page

1. Pass and return primitives as value to and from functions
2. Pass objects as const reference to functions and omit const only when the function is designed to modify the object
3. Return objects which are attributes of the class as const reference and objects wich are not class attributes (especially stack and heap objects) as value!
4. Prefer references to pointers
5. Encapsulate new and delete in the constructor and destructor of a class
6. Always declare constant primitives and objects with const