The pinecone idea is wonderful, I used to do it as a kid and the birds loved it! You can also string unsalted, unflavored, butterless popcorn and dried berries on a string, which you can tie between 2 tree branches. Birds and squirrels will love that as well. Put out different kinds of birdhouses and feeders. It will give all sorts of birds a cozy place to stay. Suet cakes are great for attracting other kinds of birds, larger ones like Woodpeckers and Grackles and things.
Don't forget the little creatures on the ground! To provide lovely homes for toads, frogs, turtles, mice, voles, rabbits, etc., lay hollowed out rotting logs over on their sides on the ground. Create a woodpile out of chopped wood and broken twigs and dead leaves if you have them. Stack rocks on the ground so that you create some little crevices in between them. Provide lots of growing greenery on the ground for things to hide in. Provide a water source like a tiny pond or water pan for creatures to drink/bathe in. Things that live on the ground need lots of cover to feel comfortable. I let sections of the grass in my own backyard grow really tall, and I see rabbits, turtles, snakes, toads, voles, all the time!
You can plant things like Butterfly Bushes to attract butterflies and bugs, which in turn attract things that eat bugs. The variety of wildlife around butterfly bushes is astounding!
Good for you that you want to give animals a happy home in your yard! You are doing a wonderful thing.