Choose a bright, sunny location for your garden. Butterflies, like flowers, like the sun and temperatures of 85 degrees or higher. Have you ever noticed you see more butterflies on sunny days than on colder, cloudy days? This is why.
Plant larval or host plants for the adult butterflies to lay their eggs on. Once your butterfly has laid eggs on the host plant, it will grow in the larva, break out, then begin to consume the leaves of the host plant. Plant a variety of host plants to attract different types of butterflies. Some common host plants are: milkweed, marigolds, parsley, and clover. Check with your local nursery to see which are viable in your locale.
To keep your butterflies around you garden, you will need to plant some nectar plants.
The nectar plants provide the "food" that your adult butterfly feeds on. You will see the butterfly using its long tongue, called the proboscis, to obtain the nectar. Some common nectar plants are: lantanas, catnip, and lavender. You can also lay out pieces of fruit for the butterflies to eat. Kiwis, bananas and watermelon attract butterflies. Also, try watering and making puddles in your garden. "Puddling" is an activity of adult butterflies whereby they huddle in groups, licking water from a puddle. You can even add a sports drink to your puddle; these drinks are sweet and contain sodium which helps the butterflies.
Go to your local nursery and ask what plants they have that would act as host and nectar plants for butterflies. Plants are sometimes marked as being "butterfly friendly." Visit more than one nursery since different ones may have different plants. An added bonus: plants that attract butterflies oftentimes attract hummingbirds as well.