If you build it, they will come
The size of a yard has little to do with how much wildlife it attracts. Creating habitats that meet basic wildlife needs is what will populate your yard with area wildlife. Your plan may be as general or specific as you desire. If the wildlife you are hoping to attract is something very specific, some research will be required. If you are trying to attract specific butterflies you will find that they feed on very specific host plants. For example, the Karner Blue butterfly is endangered and found primarily in Wisconsin. The caterpillar feeds only on native wild lupine. But wait, if that's all you plant the adult butterfly will quickly fly off in search of milkweed hosts to feed on.
Some initial parameters to consider are your soil conditions, sunlight, and growing zone. Write a list of native plants that will thrive in the conditions you found in your yard. Includes plants in the aster family such as coneflowers and sunflowers. Dogwoods, serviceberries, and viburnums and mixed grasses should also be included. For more plant options search our plant gallery using the Attract Wildlife Category. While you do not have to stick with 100% natives, pay special attention to how non-natives spread. If it is listed as even mildly invasive or aggressive, I would choose an alternative species.
Nothing attracts wildlife like a water garden. If the budget is tight, consider a pondless waterfall or decorative fountain. Water is essential for drinking, bathing and wildlife reproduction. These types of water sources not only provide the water but an abundance of additional wildlife. The filtration and movement of the water in circulating systems will also reduce the mosquito population rather than add to it.
Cover & Protection
It is important to mix the edge treatments of a water feature as different wildlife species will prefer different types of cover. Some prefer the canopy of shrubs while others prefer ground cover or grasses. While you can provide many places for wildlife to live using only specific plant selections, you may also want to create some yourself. Often these habitats can be found by mistake. A brush or compost pile, fire wood stack, or a dying tree can all provide excellent habitat. So before you rush to remove an old scrag, consider working it into the overall design. As far as some of your new friends are concerned, it is actually a 5-star hotel. You may also consider constructing some more formal housing such as a bird house or a bat house.
A Place to Raise their Young
It is important to research all phases of the life cycle when considering rearing habitats. This is another area where the construction of a bird house or nesting box may be necessary if other habitats can not be provided. If your lot has no mature trees, for example, a bird house built on a tall pole may be required until your trees mature. Consider masses of host plants, in which case you are making an "offering" to the caterpillar stage that you expect to either outgrow the consumption or replace the hosts each year. You can look up specific host plants for butterflies here. As your plan progresses keep in mind the best thing you can do for all your new neighbors is to maintain the garden in an environmentally friendly way.