Just a quick note to address the fixer I use.
I have only ever used Krylon Matte Finish 1311 spray.
http://www.krylon.com/products/matte-finish/It went over the pigments fine and did not distort them at all.
It has never given me a problem and I have used it on hundreds of miniatures over the last few years, except once.
I used a really old can, with only a little bit left in the bottom of it. I probably should have shook it up more as well.
It left some white spots on the minis that weren't terribly noticeable that eventually went away.
I highly recommend it.