Make sure you add them to a clean container, and use a separate dropper pipette for each raw oil, otherwise you will mix them in unexpected ways.

My favorite effect in recent memory has to be the floating landmasses on Pandora in Avatar. The first time they fly through in the helo was definitely a jaw-dropper.

Use the eye dropper tool to sample the darkest green color, then paint the four corners with a little grunge in that color.