Look at a reference drawing and pay attention to how the petals transition from light into shadow. Then, create a visual blend by painting colors next to each other that are very close in value. That will create a soft blended effect.
You can experiment with different shades of the colors you would like to use on a separate scrap of paper. Try sketching out a single peak/curve and just shading that....
If you are focusing on the center, which looks best, you would shade both sides a medium tone of the color, and blend using your finger or a tissue, moving...
You can! Closed hibiscus petals will work well in Jamaica. In fact, when you go to Spanish markets or stores, they often have these. You can also make punch and...
No, the petals release essential oils which relax your muscles and also smell good. You can keep the petals in the bath salts while you are using them.