When doing freehand embroidery on cotton patterned fabric, start by choosing a smooth, tightly woven cotton that holds stitches well without puckering. It’s helpful to use a lightweight embroidery hoop to keep the fabric taut and prevent shifting while you work. Since patterned cloth can make it harder to see your stitches, use contrasting thread colors to make your design stand out. Planning your design lightly with a water-soluble pen or chalk can guide your stitches without damaging the fabric. Work slowly and evenly, using simple stitches that complement the pattern rather than compete with it, and be mindful of the fabric’s weave to avoid pulling too tightly. Taking these steps will help your embroidery look crisp and balanced against the background pattern.
Pick an aspect of the design (e.g., the wings) and just do those -- that way there is consistency across the whole piece.