First of course your lake needs to be in a good flyway. But lets assume the birds are flying by and just not stopping often. Then my answer is food and shelter. Those are the two things that will set your lake apart and make the birds hit the breaks and stay a while. The only product I have found at this time is the floating island. I have been utilizing this tool for only about a year and I can't believe I waited so long. Its a simple idea really, the island is self buoyant and needs only to be anchored. You plant basically any water loving plant on these island in a bed of peat moss and the roots grow through the island and into the lake water. The plant roots uptake the nutrient in the water and grow quickly. When it comes to attracting waterfowl I select plants like Pickerel Weed, Smartweed, Millets, Rices, or Wild Celery. These plants will provide both seed forage and attract aquatic and terrestrial insects. Depending on the time of year and the type of waterfowl both seed forage and insect forage will make up a huge part of their diet.
Once you provide food, shelter is just as important. I plant a few of the islands with common reed to create small areas where waterfowl can hide and depending on the species even roost. If waterfowl begin using your lake to roost you have just created a lifelong bong with that location.