Gryffindor: just tries to avoid getting any on their finger, if it ends well they may try a pattern

Ravenclaw: always trying new methods- tape/glue around the edges, water marbling, eraser pens

Hufflepuff: just aims for a colour and achieves a nice looking coat. The real struggle is not messing it up while you wait for it to dry afterward

Slytherin: initially shoots for an intricate pattern or an actual image, if they fail they just take it all off in a huff