The choice for colour scheme was a little trickier than I had imagined. I wanted to use the colour of the rusty fabric and nails, but wasn't sure what the complementary colour would be. I found a website that was of great help.
There is a Colour Calculator tool, which allows you to adjust the saturation and lightness/darkness of the colour and to choose the harmony (in my case, complementary). Very useful indeed.
I made the necessary adjustments and the complement to "rust" (orange) is a bright primary blue.
Oddly enough, this is a favourite colour scheme, but I have not used it much in stitchery, so this should be interesting.