Never open the window unless ordered, but simply hold up your license, insurance and registration for the officer to see.
Seems like just barely cracking your window to slide out the license would raise a huge amount of suspicion to the officer. He would then ask you to exit the vehicle and try to probe around.
Seems like a better way is just to not talk that much and have all of your documentation handy before he walks up so he doesn't have to stick around your window too long. Also, when the officer asks you "do you know why I pulled you over", always say "I don't know" - he is just collecting evidence.
Why am I not surprised...