If you feed birds - don't use generic bird feeds - most of it contains a lot of millet - which will be used by sparrows and starlings, and pushed out or spilled by other birds.
Cracked corn will attract ground feeding birds, including doves.
Black sunflower seed and safflower are used by many finches.
Suet (cooked deer, elk or beef fat) and peanut butter area used by many birds including woodpeckers.
Birds that don't normally visit feeders, such as bluebirds, robins, wrens, and some warblers, are attracted to mealworms. You can offer them in old breakfast food bowls or shallow plastic food dishes that are too slick on the sides for the mealworms to climb. Place the bowls or dishes in an open area where the movement of the mealworms will attract the attention of the birds.
Fruits will attract orioles and woodpeckers. I use a half an orange impaled on a nail to attract orioles. the bright color may cause them to believe another male is in their area, and the juice keeps them coming back. you can also use apple halves.
Ripe bananas and grapes have two potential uses for the bird-feeding enthusiast. First, try placing several overripe bananas in a mesh bag and hang it near your hummingbird feeder. The fruit will soon attract a colony of fruit flies. The hummingbirds will drink the sugar water and alternately visit the "banana bag" to capture the fruit flies, which provide a good source of protein.
A second use of bananas and grapes or grape jelly is to place some on a feeder tray in the spring and early summer, especially during the warbler migration. Peel one side or split the banana lengthwise to expose the fruit. Tennessee warbler, summer tanagers, and Northern orioles may eat at your feeder.
Here is a great site for determining what type of birdseed to use: Seeds and Grains for Birds.