I recently finished an 8x8 painting of a Canna Lily, titled "Late Bloomer" because when I took the photo last fall, it was September and my Cannas were still putting on a spectacular show.
Step 1: After laying down the initial sketch in pencil (I used the "grid" system and separated my paper into 4 quadrants to maintain aspect ratio) I then developed my palette, to better understand value relationships and cool-to-warm ratios. My palette here consists of Winsor Yellow (cool), New Gamboge (warm), Viridian & Cadmium red & orange (warm), Alizarin Crimson (cool) and Violet Lake (cool). I added Winsor Green to develop the final dark shadows.
Step 2: I laid down a wash of cool yellow, followed by wet-in-wet of warm yellow. A little more wet-in-wet of cadmium red on the outer petals.
Steps 3 & 4: Allowing each layer to dry, I began the process of building up the red values, going from warm to cool.
Step 5: At this point, I needed to see what my contrast would be like once I added the deep background. I mixed up Violet Lake, Alizarin Crimson and Winsor Green and laid down a wash using very little water.
Step 6: After allowing that layer to dry, I could see where I needed to deepen the warm & cool shadows on the Canna. Then it was time to put my paints away and stop before I muddied it up!