After my initial attempts, I decided it was time to try something challenging.  I went for a complex picture with a lot of fiddly bits in it.

It proved to be frustrating.  It was much more work than I anticipated.  It took me a long time to finish it.  I was able to use some of the ideas I had explored earlier, darker borders around shapes, colour contrasting in similar shapes, such as the leaf cluster just by the bottom of the well.  I had good feedback though.  The blue circle gave it a kind of unity, similar to the mandala.  I think the picture is too busy to be improved on in any way.