By far the most effective thing you can do is reduce the size of your grassed lawn. Shrink it down to what you actually need - not what somebody else thinks you should have. At our place, roughly one-quarter of our yard is lawn (grass). That's all we need and all we need to maintain (I have better things to do). The rest is "birdscape".
To a bird, a big grassy lawn is like a desert; with almost nothing to eat, no water and no place to hide, rest or nest. This time of year (unlike up north) is easily the best time to plant trees and shrubs. Less lawn translates into more places to plant these birdscape plants.
All birds need water every day, whether the weather's freezing or super-hot. Water (like in a birdbath) is not only inexpensive, but will attract species that don't eat seeds, such as Robins, Wrens, Mockingbirds and Flickers. A "birdbath" needn't be an expensive, ornate thing - anything that holds water and doesn't embarrass you is fine.
Another inexpensive thing is a "brushpile". It's just what its name implies - a random pile of woody branches (tree trimmings?), leaving lots of nooks and crannies inside for birds to find. Every yard can and should have a brushpile; it's a mini bird sanctuary.
Feeding only good, fresh seed is crucial. If you run out, so be it. The birds can simply eat something in your birdscaped yard. If you ever use cheap/stale, grocery store or big box seed, however, the birds will leave that feeder for good! A wild bird gets only about 10% of its food from birdfeeders. So remember - just because a feeder is empty, it doesn't mean you have to fill it.
A feeder that goes empty for several days is like a restaurant closing - the birds won't starve; they'll just go somewhere else. And if your yard is birdscaped, they'll still be in your yard.