Use closed-back headphones and avoid open-back or cheap earbud models. Closed-back headphones are designed to prevent noise leakage from the headphone speaker.
Turn the headphone volume down. The lower the volume, the lower the chance of noise leakage.
Mute click tracks and any guide tracks that will not be part of the final mix. These elements will interrupt the final mix if they leak into the vocal microphone.
Move away from the microphone. The chance of bleeding increases when loud headphones are very close to the vocal microphone.
Use low-pitched click tracks instead of high-pitched click tracks, as they have a lower chance of bleeding.