I would do alot of scouting and see what the ducks are doing. It depends on the size of the hole too when it comes to decoy numbers. You always want it to look natural. Sometimes bigger isn't always best. If you always see a ton of ducks there then I would probly use alot of decoys but if you have been seein a smll group of about 15 to 30, I would only use about a dozen. On one of my holes it's about 4 acres and I have never seen more than about 30 or 40 mallards on it at one time so I don't use a lot of decoys and I always pick them up when I'm done. Last year Me and some of my friends used only 9 decoys a few days and killed our limit every time. If the wind is right always try to make it where they have to fly in with the sun in their face so it is harder for them to see you. There's my 2 cents. :salude: