I choose not to imagine colours, because I haven't heard many good descriptions of colors. Color descriptions I normally heard were: the grass is green, the sky is blue and my typical response would be: yes, I know, I went to the same kindergarten you did.

As to matching clothes I have a system of where all my clothes go, and I have lengths of pin where shorter is lighter and longer is darker.

I don’t care about colour, I know about them but that’s about it.

colour is entirely a learned thing to me. I have to make a deliberate effort to recall the colour of my own hair, eyes etc. It just doesn't impact anything day-to-day.

In terms of clothes, I have sighted advice to look reasonable for work. Black goes with most things for lounging around and being social.
Colour is probably the least significant aspect of sight for me: lighting comes up quite often, as does needing to read things of course As a a white child, I struggled to get the concept of race and skin colour. It took a while to expand from the black and white of chessmen to learning that it's not really like that in the world.