I have added some spots of masking fluid where I wand water or dew drops on the petals. They appear very yellow and flat but, once the mask has been removed, it will give me a white surface to paint in the tonal differences. Roses, and in particular with dew added, are a bit os a cliche, but this rose from our garden is such a rich and intense colour, it had to be painted. I observed actual dew on the petals as the shape depends on which part of the flower it lies. Artificially added water drops with a hose presents a less natural state and, usually has too many. I have started with the darkest petals in shadow and will work from dark to light in most cases here.