Try starting here: http://www.archives.gov/veterans You may also find it valuable to talk to as many family members as possible, particularly those contemporary with your grandfather. If nothing else, you can often find out what unit he was with, and then read up on what that unit did. Sometimes little clues can be quite important.
I knew, for instance, that my father said that "no one ever let him drive the bulldozer" because he was the only guy in his unit that could type with any facility. Turns out he was in a combat engineering unit in the Philippines that was in the thick of things. The only two things he'd ever tell me were "couldn't drive the bulldozer" and a story about a typhoon while he was on a troopship.
But that led to a history of his unit.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.