Our gr in our lawn has suffered from the last couple of years with drought. What can I do to fix it?

We have had a cuple of years of little rain and our lawn has suffered tremendously. What can I do to re seed it to make it thicker, greener, nicer. I know to plant in the fall. Do I cover with straw to keep moister in? We live in notherern WI where the winters are long and cold.