Put out a source of water. If it freezes a lot get a heated bird bath. That is a huge attractor of birds, especially in the winter. Brush or bushes that keep most of their leaves are great for little birds to hide in when it's cold too, or from predators. Vary the type of seed you put out, put some wild bird food mix, some black oil sunflower, a thistle feeder or two, throw some random seeds on the ground for birds that like to ground feed more. Hang suet feeders out for woodpeckers and chickadees. But the biggest thing that really keeps birds coming and feeding in your yard is also having a consistent source of water too.