How do I legally charge a credit card fee?

Can you walk me through the process of legally charging a credit card fee? I understand that there are certain regulations in place to protect consumers, but I'm not entirely sure how to navigate them. Is there a specific percentage I should charge, or does it vary based on the transaction? Additionally, do I need to disclose the fee to my customers in a particular way? I want to ensure that I'm compliant with all relevant laws and regulations while still running a successful business.