1. Prepare Tennis: Select the tennis ball to sign. It can be brand-new tennis or used tennis.

2. Prepare signature tools: choose the tools suitable for signature. Common signature tools are permanent fine pen or signature pen. Ensure that the ink color of the signature tool is clearly visible on the tennis ball and will not fade or blur during use.

3. Prepare the signature area: Choose a position suitable for signature on the tennis surface. A common choice is to sign on one of the two sides of the ball.

4. Signature: Sign the tennis ball with the selected signature tool. You can choose to sign directly on the surface of the tennis ball, or you can put a personal signature label on the ball. If you want to keep your signature on the ball longer, you can use a little force to ensure that the ink or label is firmly attached to the tennis ball.

5. Drying and protection: After signing, let the ink or label dry fully. Avoid touching the signature to avoid accidental erasure or blurring of the signature. In order to protect the signature, you can put the tennis ball in a transparent tennis box or use a protective ball cover.

Signed tennis has certain commemorative value. Before signing, please make sure that the tennis ball you want to sign is your own or authorized accordingly. For some important games and professional players, there are specific signature rules and requirements. In these cases, it is best to follow the relevant guidelines and regulations to ensure the compliance and authenticity of the signature.