I finished my Poppy painting last week. I used plenty of different techniques for it, mostly using thicker paint than in the past, which gives the whole thing a much richer texture, more like acrylics than watercolours.
But I still made the most of the watercolour medium, in that I was able to lift the colour where I needed to have highlights. Over the last few weeks, I've been putting together a chart of all my watercolour paints, which shows the exact colours, how opaque or transparent they are, and how easily they lift. This has been very useful in anticipating how the different paints will behave.
I masked the whole center of the flower with low-tack paper before I painted the petals. This is a technique I had learned from Elizabeth Kincaid's book, which I've now used a few times. It gave me a lot more freedom when painting the petals. I also used masking fluid to mask the stamens while I was painting the other items in the center. Again, this enabled me to paint more freely, without having to be too careful where the paint went.