1)Make a small "puddle" of your blue color. Now pull a portion of it (about 1/3rd) off to the right,... then add a bit of white into it to lighten it up. Use as your highlight color.
2)Leave about 1/3rd of it in the middle,.. untouched. This is your base color,.. you'll need it for glazing/touch-ups later.
3)Pull about 1/3rd to the left,... then add a bit of black to darken it. Use as your shadow.
4)break the piece down into its basic elements,... hills and valleys. Apply highlights to hills,.. and shadows to the valleys.
5)after dry,.. glaze a few thin layers of your base color over everything,.. this will help unify the colors.
Hope this helps,...