Tonal contrast and how to make it work for you in a painting

Talking of TONE, this is a watercolour I painted over the last few days which might illustrate the subject.

I took this photo of some clematis in our garden last year.  I loved the cast shadow on the lower flowers and the tonal contrast between the sunlit top flower and the background.  Sunlit subjects always have these extremes of tone which make for an arresting image both in a photo and in a painting.

I made a drawing from the photo.  

Then I mixed my colours.  I put aureolin and raw sienna side by side for the yellows.  Permanent rose and cobalt violet for the pinks.  For the greens I loosely combined Winsor blue, quinacridone gold and aureolin.

When I mix my colours I think about all the elements in the painting and which colours I'm going to drop in for them.  And then I always have to think how I am going to mix my darks.  Because if you want to make a painting with plenty of tonal contrast and impact, then the darks very important.

How to mix darks without making the colours muddy???

Well I'll tell you how I do it next time!  And I 'll show you my palette with the colours mingled.