A wood duck is a costly mistake when teal hunting. You can distinguish teal from woodies by looking for the square tail on the wood duck. Wood ducks don't usually fly in a groups of more than 3-4 either. A wood duck in flight will almost certainly move their neck and head up and down, if you see this, don't shoot. Blue wing teal have a very large and very distinguishable blue patch of their wings, it's very visible in flight.
Shovelers have a wide, flat bill, unlike the shorter bill of the teal.
Look for blue wing teal early in the season and the green wing teal to start migrating towards the middle or end of the season. Teal are not hard to decoy, but most of you shooting is going to be opportunistic pass shooting. A teal rig can consist of just about any decoys you have. It's probably wise to stay away from using any drake decoys with lots of color this time of year, as most drakes are not in full plumage yet. A rig of more than 18-24 decoys is probably overkill for teal hunting.