The foundation of your success, it pretty much needed to even platinum it.
Always double tap, there's no reason not to.
ALWAYS strafe, LB on Controller, B on Keyboard.
Don't flutter, it doesnt really help and you need all the time you can have, so just dont.
Try to shoot the ducks at every opportunity, you're probably not gonna get a good score if you keep stalling on the ducks.
Oh, and if you're going to for the Ur the best trophy and not the platinum, then restart when you miss about two or three ducks, you wont be able to get 45 if you miss some.

This is the real deal, basically an exploit that helps alot.
I dont know if everybody know about this or im just a special snowflake to find this, but if you shoot the sniper and reload, you usually have to wait a second until you can shoot again. who neeeeeds that?
Basically this exploit works by pausing and resuming immediately after you press shoot to reload, and during the countdown for time to resume, the duck goes all dio and reloads the gun, so it gets rid of reload times.

TL;DR pause while reloading so theres no reload time.

Now, while this is useful, it can easily throw you off, and make you mess up so you shoot the wall alot. so use this new power with responsibility.