1. Using inline to replace #define when there are paramters
2. Using unsigned int only for bit-operations
3. Using fixed-width type int e.g. uint8_t, int8_t, etc.
4. Using const as many as you can to avoid mis-modification
5. Using static as many as you can to limit the functions/variables scope
6. Using volatile for interrupt or mutti-task shared varaibles
7. Using {} even there is only one line code in scope
8. Using const to replace #define Marco
more rules later