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Learn to judge distance by the appearance size of the target.
An early season teal is easier to kill than a migratory mallard, and the mallard is 2x further by appearances.
You don't need a 3.5" 12 gauge, 3 inch is plenty for 90%, but a good 10 gauge, while heavy, can shoot very nice.
Join a winter skeet league for practice.
Use ammo with similar velocity when practicing.
Consider heavy shot, like tungsten, rather than steel, for days afield.
Get a good job, you're gonna need a boat eventually, and a truck, and a dog, and then a bigger boat.