Get students paying attention to types in Python; although type declarations aren’t explicitly required in Python, they still exist and are crucial to understanding how Python manages data.
Train students to draw pictures of code traces through namespaces, objects and function calls because the benefits of drawing these processes helps them avoid common mistakes.
Reinforce that certain types in Python such as lists are mutable while others (e.g. strings, tuples) are not. Students have difficulty tracing code that uses mutable types because they often forget this.