In the UK book 'The Complete Style Guide' by Mary Spillane or in its US equivalent 'Color Me Beautiful Looking Your Best' there is a little section called 'Wardrobe Planning for your season'. Here Mary puts together a standard 12 piece mini co-ordinated wardrobe capsule, but varies the colours for each sub season (she's working with the 12 seasons in the later CMB books, see the book for more details).
The items she has are as follows:
12: Sweater or swing wrap
If we allow substitution of extra pants for 2 of the skirts, my plan matches hers if I add an extra toning sweater or cardigan wrap. I don't knit so it'll have to be sewn or purchased.