How do I add a token to my assets list?

Could you please elaborate on the steps involved in adding a token to my assets list? I'm relatively new to the world of cryptocurrency and would appreciate a detailed guide. Specifically, I'm interested in understanding how to identify the token I want to add, whether there are any specific requirements or restrictions, and the exact procedure to follow for integrating it into my portfolio. Additionally, I'd like to know if there are any security considerations I should be aware of before making this addition. Your assistance in navigating this process would be greatly appreciated.