Often, you just have to go with the flow and see what happens. That's exactly what I did with this piece of art. I let the colors flow.
I used liquid acrylic paint. You can buy it, or you can dilute your acrylic paints with lots of water.

I used a 40 × 40 cm stretched canvas for this artwork. The 300 g/m² cotton fabric is stretched over a wooden frame. The wooden frame is about 17 mm high and 38 mm wide.