I started my mission by making a decision to give up a few of the plants that are considered invasive in my area - namely, the burning bushes and multifloral roses that have spread and are drowning out native flora. Two seasons ago, the burning bushes were removed and I begun cutting down the multifloral roses. There are offspring of both of these invasives growing profusely about that need to be dealt with. I also discovered Ivy growing up the trees to the north side of the yard. These certainly were not things I bought and planted and they can climb trees and kill them.
It's been advised not to remove all your leaf litter. What a great excuse to not have to rake leaves, or at least not all of them! We do benefit from our location and with the woods around us. I have been amazed at seeing how birds are using those fallen leaves to look for insects that might be overwintering within or under them. Even letting native plants to spring up in a back section of the yard has also provided native seeds these birds would feed on during the winter. The added benefit of this little wildflower garden - it didn't cost me a dime to put in! Here, White-throated Sparrows and Dark-eyed Juncos feed on seeds of wild asters (I have not identified the plants specifically).
Sometimes it takes a little creative thinking and investigating to see how you can work with the space you have. My birding friend always called our lot "a nature oasis" as we've had many species of birds and wild animals come through. All are welcome and all bring a smile to my face. I can sit with camera in hand for hours enjoying the creatures that come through and know that as I continue to add plantings that will attract animals, they are able to share what I call home. They have food, water, and shelter to roost or raise young. It is a great feeling to be able to give back and if every person who owns their own home could give just a small section back to nature, it could mean a lot for animals who have been displaces on account of our exponentially growing population.
Check out your local Audubon Society chapter for information on native plants you can buy. or a local garden club or plant store. Many can offer suggestions to help you invite nature into your yard.
For Connecticut area residents, the native plant sale http://www.menunkatuck.org/index.php/conservation/plant-sale-for-the-birds/native-plants-for-sale/
National Audubon Society http://www.audubon.org/
National Wildlife Federation http://www.nwf.org/
Benefits of using native plants:
http://www.epa.gov/greenacres/
http://www.ncsu.edu/goingnative/whygo/benefits.html
http://www.ct.gov/caes/lib/caes/documents/special_features/nativealternatives.pdf