Make sure you record extra footage at the beginning and the end of the scene. Press the record button of the video camera for about 10 seconds before you shout “action”.
This will ensure that there is extra footage at the beginning so that the video camera will start smoothly and not clip out any voice or action. It also makes for easier editing as you have sufficient footage to cut the scene.
Likewise, at the end of the scene, do not stop the camera immediately after you shout “cut”. Let it continue to record for 10 seconds.