How do I add USD to my PayPal Wallet?

For those seeking to enhance their PayPal Wallet balance with US dollars, the process can be surprisingly straightforward. Could you elaborate on the steps involved in funding a PayPal Wallet with USD? Specifically, I'm interested in knowing whether there are any limitations to the amount I can deposit, as well as the available methods for transferring funds. Furthermore, is there a fee associated with these transactions? Lastly, is there a recommended way to ensure a smooth and secure deposit process? Clarifying these details would greatly assist in my understanding of how to efficiently add USD to my PayPal Wallet.