FABRIC DYEING & PAINTING TECHNIQUES
Fabric Painting Techniques - The Sewing Loft
Draw designs with a laundry marker. Sharpie will work, too, but doesn't last through several washes very well. But that faded look may be what you're wanting...
Painted Threads Projects: Making Black and Bloom all Over
Fun With Fabric Painting: Supplies and Techniques
Painting on Fabric: How to Keep Your Edges Sharp