Analogous colors
Colors next to each other on the color wheel usually create a smooth, coordinated feeling. Examples include blue with blue-green and green, or red with red-orange and orange.
Complementary colors
Colors opposite each other create stronger contrast. They can be energetic and clear, but one color often works better as the dominant hue while the other acts as an accent.
Triadic colors
Three more evenly spaced hues can create variety without relying on a single opposite pair. Adjusting saturation can make a triadic palette bold or surprisingly soft.
Muted versus vibrant matters
Harmony is not only about hue. Dusty versions of several colors may coordinate beautifully even when their brighter versions feel too intense together.
Texture changes perception
Fuzzy, glossy, heathered and variegated yarns can change how a color reads. Use color theory as a starting structure, then judge the actual yarns together.