I love this question! My mom was one of the originators of this forward-fashion trend when I was just a very young child. I'm a winter :).

She taught was was called "Color and Line", which was about the colors that are best for your skin tone/eyes/hair and clothing styles best suited for your body. She owned a fabric store, taught sewing lessons, sold and repaired sewing machines, so Color and Line was a natural extension of her business and expertise and how she served our community.

In a nutshell, for the color part, she analyzed if your skin tone was better suited for colors with blue undertones or yellow undertones. The colors that are in these ranges can be warm or cool, and should be the colors that are worn closest to your face. She did this with drapes of solid colored fabrics around the neck and shoulders and it was easy to see which colors makes the face and eyes look brighter versus sallow and tired. She knew how to "power-dress" wearing a dark blouse and a light jacket, and how to keep the "pojnts" to no more than 5. Points are accessories, like scarf, belt, jewelry.

For clothing styles, she analyzed what is your longest part of your body and the shortest part, based on head to shoulder, shoulder to hip, hip to knee, knee to foot. My longest is my hip to knee, and my shortest is shoulder to hip. So the strategy is to accentuate the longest, camouflage the shortest, to look taller and in more proportion. So if I wear waist-high pants with a tucked in shirt and a belt, I look short and all boobs. 

My favorite memories was when she would do Color and Line consulting at home for a local agency that employed nannies. All of the nannies would be sitting in a circle in the living room and would have an "aha" moment that they could brighten up their style and still be effective care-givers, that these 2 goals were not mutually exclusive. My mom also served women transitioning between incarceration and release, unsheltered to sheltered, battered women, differently-abled women, etc. A close childhood friend had a malignant brain tumor and didn't grow much after toddlerhood, my mom helped her design clothes and colors for her teeny body so she didn't have to be a 5th grader in toddler clothing.

And then there was her advice on how to have your partner look radiant in the bedroom with the color of linens, bedding and walls.

You should be able to find the books in the library or on-line. I remember "Color Me Beautiful" as being an industry standard. My mom wrote "The Magic of Color and Line"; on eBay I can see the Table of Contents page which gives some good information, 

As I read what I wrote, in this current era my explanations and descriptions seem rather sexist. Yet back in the 60's and 70's, she helped a lot of women succeed in the business world and employed many women in her fabric store.

Best wishes and color it up!