I used my basic Guitar watercolours, and added white Perfect Pearls to the petals, and gold Perfect Pearls to the leaves. I know that everyone is talking (and using) of the Peerless and Gansai Tambi Watercolour sets, but I think my everyday ones worked out ok. It is my first card using the Ranger watercolour paper, and it is really good. Much better than anything else I've tried. The colours run well, and it didn't buckle at all despite the amount of water I used.
These colours happen to match the Color Throwdown Challenge, (and are one of my favourite colour combos) so I will enter it there.