I've decided to start on the background, this is due to the dark tonal values on the right. The waterlily has extremely delicate tones, so I needed a tonal guide of the overall composition, so the petals don't look too faint. The background is far from finished, I've just blocked in the basic colours and tonal values. I'm going to let this dry, then start work on the flower. Once I have most the detail of the flower I can work out how detailed the background needs to be, so it doesn't take away the focus from the flower.
Whilst this dries, I've another waterlily oil painting to start, so I'll get to that onto canvas tomorrow.