Avoid pesticides, some of them can kill butterflies.
Grow natives, they are the easiest plants to care for, attract pollinators and all around are better for the planet.
Plant where it is sunny, butterflies feed in the sun.
Think in red, yellow, orange, pink and purple flat-topped blossom flowering plants. Butterflies are drawn to colour.
Create a butterfly spa. They prefer full sun, flat rocks, and hanging out in damp sand where they can drink water and unwind.