Faceoff tips

My son, 12, is slightly above average and one of the better kids on his red team. He also plays club and has attended a faceoff clinic for the past 6 months so he's learned a lot from those coaches. The problem is that he's on the smaller side so he has some trouble when squaring off against bigger kids. Any tips, advice, cheats I can pass along to him to help him out? Lacrosse is only been growing in my area over the passed few years and wasn't around when I was growing up so I didn't get the chance to play so I only know the basics. Any links or advice is greatly appreciated.