What you'll need:
Paint (I used acrylic, it went on smooth but dried rough so I'm sure there's a better paint to use for it, I'm just not that knowledgable of paints. If there is please share in comments)
Possibly a soldering iron
Step 1: Choosing A Mini figure
There are some other sci-fi types out there, my favorite was part of series 11 I think. It's the one with the bulky shoulders.
Step 2: Detailing
First, decide if you want a helmet or not. If you do then you should get a pocket knife (I used a razor knife for finer areas) and scrape off the paint that's already there (if needed, on one of them I used a sharpie since the helmet was black) use the pictures above as a reference on how to hold the knife so you don't take out chunks, yes you hold it so you drag it across instead of cutting into the face of the material. Then paint in the lines for the vizor look, use any color you want!
Now for the RIG. Paint/sharpie a thick black line part way down the back to do an outline. Then use the same color you used on the vizor just inside the black line you made prior and put thin black lines across. If you feel really artistic, you can paint up a stasis module!