I'm having a hard time finding a small bottle of flat orange (for a figurine's hair - a Martian). Any suggestions or, any ideas on what colors could be combined to get flat orange?
Mixing red and yellow is of course how you get orange, but not all oranges can be obtained with all reds/yellows.
Your question kind of implies you have an orange you like, but want a flat version. If I am wrong, disregard. But you can make any paint "flat" with a clear coat. I did that recently on an F-104, I tried mixing and could not get the orange I wanted. The orange I wanted I had, but it was the old-fashioned Testors square bottles, and quite glossy. It turned out good with a nice layer of satin on top, you can get duller effect than this.
No, I don't even have a good shade of orange. It's for a character with light red (thus orange) hair. The link that @urumomo provided has a shade that will work.