: Ensure you are using it in a low-latency monitoring mode within your DAW (FL Studio, Ableton, Pro Tools, etc.) to allow the singer to hear the correction in real-time without delay.
Use it as the very first plugin in your vocal chain. You want the tuner to see a clean, dry signal before compressors or delays "smear" the pitch information. Pro Tip: The MIDI Input waves tune real time tutorial