Protecting your head is something that should be taken very seriously.
The England and Wales Cricket Board actually recommends a helmet with a faceguard is worn by anybody up to the age of 18 batting against a cricket ball.
Even if you're not batting against fast bowlers, a helmet will protect you against an accidental full toss or a top-edged sweep or pull shot.
Make sure the faceguard is properly adjusted so the ball can't pass beyond the space between the grill and the peak of the helmet.
Make sure the helmet is securely held in place by the chin strap as you'll be given out if your helmet comes off and hits the stumps.