Being successful in the fields starts with a lot driving. When seasons kick in and the crops are coming out combined with colder temperatures, you will need to watch the birds and pattern them. Watch for when they fly to feed and or locate them in the fields.
If if you can get that part down then it's time to set up on them and hunt. Biggest priority in the field is your ability to hide good. Stay hidden in the fields and you will start to find success. Then the addiction starts!
^^^^This^^^^
I would suggest as well to go to the property(s) you are going to hunt on and scope it out so to speak to see for your self where the birds are, if there is water or not, and so on. Have a good set of binoculars to make it a little easier on one self.
Also ducks will come in on goose decoys. Ive shot ducks in a field with 80 goose decoys and only a dozen ducks... Honestly I've even used just geese and a mojo. Beware of the Mojos though when it comes to geese, they hate them! The biggest thing is just being where the birds want to be. If you can find them and hide you'll have the most success.
Also, if you haven't looked at full body goose decoys you are in for a bit of a shock. They are super expensive and you need a fair amount. I usually hunt with a friend and we combine ours. There are very few situations I can think of where I got away with about a dozen, those were in places I honestly could have probably killed them even if I sat without decoys because I knew they would be there.