Like my Architects and Clients, the concept is simple.

Any member can inquire a stylist to give a makeover to their sim (though the stylist, defined as the person who is making such request, must upload their sim). Just like in-game, a stylist gives the requirement on what must be changed/added: a specific alteration of clothing type or additional. You can inquire what It will help If the stylist provides biography/details of that sim, such as ethnicity, social level/class status , simology, career etc. Basically, anything. A picture helps.

An architect (which is the person that takes the offer) can only change the sim's fashion sense features (face makeup, clothing, hair, accessories, plus tattooing is included). If possible, trigger makeover room so that you don't mess up the sim beyond the fashion possibilities. When finished doing a sim make-over, the Stylist upload their final result here (with a sim for download file) with a screenshot.

Hi, so should I just find a random sim, add them to my family, learn about them, then give them a makeover?

No. From an actual person, not a sim. The Interaction happens between two people: the stylist and the client. Forgot to specify: Clients must upload their sim through upload wizard.