Visual dichotomy serves to emphasize one element in a composition by introducing a strong contrasting element. I’m taking as my example the fashion for extremely feminine dresses + heavy boots, back in the 90s. (We now have the dress + moto jacket trend).
This only works if the element of contrast is a true note of contrast. In the example above – the boots work because the rest of the outfit is so delicate. This offers a slightly-less-sweet note to a very sweet outfit, it makes it more youthful, more vigorous – but it still comes off as visually appealing. But. This look only works on the thin. The tiny feminine pattern of the fabric, the sheer stockings, they have to go with a delicate figure. If you introduce too much of the contrasting note, you take what was originally an ironic note of contrast and make it into a tug-of-war.
I tried this once, not because I burned to wear ironic clothing, but because I was stuck wearing combat boots for a while because I broke my foot in half. Horrible. Too old. Too thick of calf. Too thick of body. Wrong style entirely. I dropped my hemlines where they belonged. (Proportions – know yours).
Using notes of contrast must be done deliberately, and with understanding of the raw materials.
The motorcycle jacket + sexy dress look.. that is best done with feminine curves, if you want to hold on to the moto jacket as “edgy accessory” feel. (You can do any of these looks if you are very thin, but it becomes more “rocker chic”, which is an inversion – where the pretty dress is the note of contrast and the motojacket is worn, perhaps, with ripped stockings and ultra-casual hair).
Your outfit is a composition. You can add notes of contrast or make yourself entirely harmonious. You can season it with “tough” or “sexy” or “efficient” with the clever use of an accessory or two… but you must understand what you have to work with, and what your tipping points are. You also need to have some grasp of your overall style – check the style class page, please, PLEASE. https://hearthroses.wordpress.com/style-and-color-prescriptions/style-classes/
Hope this helps you find your way – and avoid the “but Betty wears this and it looks so cute – why do I look so awful?” moment when all your goodies come home from the store.