1. Provide a Variety of Different Bird Feeders.     
A hanging feeder will appeal most to seed-eating birds such as chickadees that feed naturally at tree level. Ground level platforms, or those just a few feet off the ground -- will appeal to towhees and cardinals.  Suet feeders will bring woodpeckers -- and many others, too!  So a variety of feeders, with a variety of foods will bring the greatest variety of birds

2. Offer Shelter. Shelter on a cold winter's night can be a lifesaver for wild birds.  Your spring nest box, if cleaned out, can provide such shelter.  And winter roosting boxes are available.  Another backyard haven can be a pile of brush where birds can take refuge from the elements.

3. "Best" Seed: Black Oil Sunflower Seed.   Not appealing to pigeons, sparrows and blackbirds, and accepted eagerly by small songbirds. There are many good seed blends -- but your birds will always love this pure favorite!

4. Deal with Squirrels.  You can baffle them, and/or install squirrel-proof feeders. Because the fact is: if there is a squirrel on your feeder -- the birds won't come.  In addition, though, you may start a distraction feeding area just for them in another part of your yard--keep them busy with their own squirrel toys and corn-cobs! 

5. Provide Ice-Free Water.  Water is a necessity. In cold weather natural water sources freeze over. A heater in your bath or a heated birdbath create a winter oasis--drawing birds from neighboring areas.

(Male Eastern Bluebird )

For more information about birds and birdwatching check out these links!

Cornell Lab of Ornithology
Great Backyard Bird Count
Project Feeder Watch
Birdwatcher's digest
ebird
Macauley Library of Animal Sounds
What Bird Online Field Guide