Offer a variety of food. Many small birds prefer millet and sunflower seed. Finches are drawn to thistle, and hummingbirds will need a special food and feeder. Throw out a bit of cracked corn for the sparrows. Provide suet for warmth in cold weather.
Fruit is popular with some birds, especially orioles.
Water can often attract as many birds as food. In winter, birds may have difficulty finding open water. You can purchase elaborate birdbaths and fountains, or a simple dripping hose will suffice.