One of these forums is "Miniatures", which is obviously small paintings. The size-format creates all sorts of interesting challenges, particularly in watercolour. I favour a looser approach, and so it takes a lot of restraint not to get obsessed about the detail, but rather to concentrate on the overall "feel" of the image. "Form", for me, becomes more important than "content", particularly the form of the paint.
The October challenge in this forum had an image of apples in baskets.
My submission which is postcard size:
Apples

