MySQL关系表和主键数据类型

I'm working on building a MySQL database that will have many related tables. I know I can create a primary key that is unique and auto increments, then reference that Primary Key as a Foreign Key in the related table. My question is what are best practices for Primary/Foreign key data types (int, varchar, etc..). I want to make sure I get this right the first time.I'm working on building a MySQL database that w