Learn about the basic principles of color theory, including the color wheel, primary, secondary and tertiary colors, and how colors can express certain moods and emotions. Take notes for reference.
Based on your understanding of color theory, create at least three different color palettes (sets of colors) that you feel express different moods or emotions.
Go to Piskel and click on 'Create Sprite'. Get familiar with the tools and interface.
Choose one of your color palettes and use it to create a simple pixel art design in Piskel. Try to express a specific mood or emotion with your color choices and design.
Repeat the previous step with your remaining color palettes, creating a new piece of pixel art for each one. Remember to focus on expressing specific moods or emotions with your colors.