Here are a couple of photos of the desert scheme -- I believe supercobra has posted these before, I saved them and want to give him props.
Also, I have the Twobobs Whiskey sheet:
The decal sheet does not list any model paint colors, but does list FS33711 (or sub FS33531) for the light sand, and FS30257 for the dark sand.
Also from the decal sheet:
"All USMC AH-1W initially had the tri-color (green, black, and gray) camo paint scheme. HML/A-269 chose to keep this paint scheme. HML/A-369 painted their Cobras all sand
or sand over the black and green with only the gray showing and a portion of the original markings showing. HML/A-367 initially painted their aircraft with a light coat of gray (giving a two-tone appearance with the black showing through from underneath). The aircraft were later painted sand and brown. The only markings reapplied were the bureau number (BuNo) and side number (modex)."
-- from Twobobs via Randy Smith