Big question. What everybody said above is solid advice, so I won't repeat. If you're starting out waterfowling, I'd start with puddle ducks and save the diver game for after you get the hang of puddle duck hunting, at least as to diver hunting big open water (but if you find a small lake with buffies, eyes and the like this time of the year, you can be somewhat assured there'll be a good chance you can find them back there in the fall). You are right, definitely look for where they're hanging out, but the key with that is to note THE TIME OF DAY you find them. If you see puddlers hanging out in a spot around noon, there's a solid chance they won't be there at dawn or dusk. Finding where ducks scoot to their morning feed IMO would be the best place to start. Location of the evening roost is another good thing to look for. This can change during the time of the year, which provides sort of an unavoidable limitation to scouting during the spring. Right now ducks are breeding and laying and tending to ducklings, so it may not be an ideal time to scout. August is a great time, and, of course, just before and during the actual season is really the best so long as you can find the time to go. Scouting for a field hunt IMO is much easier to do because you can mostly scout from your car, whereas scouting on marshes and bodies of water would often require a boat. The favorite spots of the resident mallards may differ from where the migrating puddlers want to be, but they are often the same.
