To mix oil paint colors, you will need a palette, a palette knife, and a small cup of mineral spirits or turpentine. First, squeeze out a small amount of each color you want to mix onto your palette. Then, use the palette knife to mix the colors. You can add more of one color to adjust the hue, or add mineral spirits or turpentine to thin out the paint and make it easier to mix. It can be helpful to start with a limited palette of just a few colors and gradually add more as you become more comfortable with mixing. Practice makes perfect!