Letters, letters, letters is what is important. Pictures of the family even if it is just goofing off. My son said that this is what kept him going at times because he could pull them out and re read them and look at the pics. Even the goofy ones with the dogs and my chickens.
Son currently in an unidentified area of Iraq but will hear from him soon as he returns to his base.
My son joined when he was 17 and has been deployed 3 times.
Step daughter turned 21 in Iraq and now my grson just joined.
So proud of them and proud of your son for making a super choice of career.
Good luck and prayers to both you and him.