Have a water feature. Many folk put out feed and plants for the birds but forget water. The addition of a fountain to our very new suburban yard last year brought so many more animals to our backyard it was stunning.
Suet (or animal fat) is another good food source that can be used to attract birds to your yard. It's a high energy food source that will attract woodpeckers, titmice, nuthatches, and other birds.
Squirrels are good where I live - we have the cute little red ones, and chimpmunks. As long as we have seeds / nuts out they things alone. Good thing because I have tomatoes, peppers and cukes growing... for our enjoyment, not theirs!