People often ask me what they can do for the troops. The simplest things are often most effective. My advice, is just say "Thank you"
Believe me, it is appreciated. I think anyone, having a tough day, struggling through the demands of work, missing home and family, would get a little lift out of hearing a friendly "Thank you." For a troop, they may be far from home, months since they saw their wife or husband, and under the stress of living with danger or having lost a brother.
You might get the same response I used to give, "I'm just doing my job." That's really how I felt. Everyone has their job, show up and do what you have to, til the job is done. When you think about it, really everyone deserves a "Thank you." For troops, they deserve a "Thank you" from every citizen in the country.
If you feel shy about stepping up to a stranger and saying "Thank you", consider the advice of the Gratitude Campaign.
Simply sign "Thank you" by touching your heart with your right hand, then lowering your hand. It doesn't take a word to do it.
I'll admit, when I first saw this, I thought it was the Arabic "Salaam" which is a slight bow, and touching the hand to the forehead or the heart. In Iraq, it is usually to the heart. It means simply "Peace" or "Hello". But even that would be appreciated. After months in the middle east, it had become a familiar and friendly gesture.