The dark-eyed junco is one of the most common (and tamest) variety of sparrow, and regularly visit feeders, especially during the winter. You'll see them hopping around with both feet while they forage.
Juncos are ground-feeding, granivorous birds - which means they primarily eat seeds and grain. Favorites are hulled sunflower seed, white proso millet, and cracked corn. Because they eat near the ground, a low platform feeder or open tray is an excellent choice. Choosing a feeder with a large oversized roof, or adding overhead protection, is helpful during winter months, since it keeps snow off the seed.
Since you are mostly likely to see juncos during winter months, a heated bird bath is a smart idea. Choose one that's low to the ground, and place it near dense shrubs, their preferred cover.
Dark-eyed Juncos build their nests fairly low, in short trees or near the shelter of fallen trees and rock piles. It also helps if you leave bushes and shrubs untrimmed until spring, so they can easily find a sheltered place to roost. They may use roost boxes during winter weather.
Preferred nesting materials are moss, pine needles, animal fur and small twigs.