I will demonstrate putting dabs of yellow here and there with a paintbrush, then a yellowish green, then a regular green, then a blueish green and finally some blue. They will randomly dab the colors on in a pleasing pattern of their own choosing until they feel it is finished. They don't have to use these colors, but they will be using at least 4 colors that mix well together. For example - oranges and yellows, blues and greens, pinks and purples etc...
When it is mostly dry they can do a splatter color to add even more pattern/texture to the design. I use a toothbrush for this.
Finally when the sea horse is dry they can add glitter and sequins wherever they want - but it is an accent, not for covering the whole painting.
It's fun the let students paint with some freedom!