I'm not an actor but used to dream of it when I was younger.
You could try watching a few war romance movies or read up on some stories that pull at your heart strings. When it comes time for the scene of waving goodbye, try to think of the pain and longing these characters must have felt and try to let go of any self consciousness.
Maybe practice at home or in front of someone (who you know won't giggle) to get used to the feeling of being looked at. In front of a mirror may help so you can practice with different expressions to see what works.
These are just ideas that I would try out if I were in the same boat. Break a leg!
