We are fortunate to live in a more suburban area - we get great songbirds here compared to larger cities. I have seen white-breasted nuthatches and yellow-shafted flickers here!
Make sure your birdfeeders are clean and disinfect them with a mild bleach solution. Moldy feeders will make the seed turn bad.
The most nutritious food for the birds is black oil sunflower seed. Unfortunately this can make a mess on the ground, so if you are planning to plant anything under there, you will need to rake out the hulled seeds. Another huge advantage to feeding only sunflower seeds is that you will attract a wider variety of birds.
The seed mixes are enjoyed mostly by sparrows and starlings, so plan your food accordingly. And if you want only cardinals, just use safflower seeds.
If you choose only sunflower seed, make sure to get black oil seed, and not the striped. The striped sunflower seed is not as nutritious, especially for winter feeding.
Sometimes when you open a bag of seed, you will discover that it has little moths in it. They aren't good for your house, but the birds don't mind - so don't throw it away!
Don't forget the suet feeders either. Suet will attract woodpeckers, Carolina wrens and chickadees. During the winter, use a high energy suet such as peanut butter. Suet blocks are still reasonably priced and can be found just about anywhere. There are recipes available to make your own, but I was never that ambitious!
However, the best attraction for birds during any season is clean, fresh water. There are a lot of elaborate, expensive water set-ups for the winter. However, I have always used a heated water bowl intended for dogs. The birds love it and it is much less expensive.