I think in English we say "look well" and it means that you are looking healthy (not ill). And to "look good" refers to having a pleasant outward appearance. In formal writing, "look good" is slightly too informal in my opinion. I'm not sure exactly what you want to say, but, for example, I might say, "it is important to dress appropriately for a job interview."

If you're speaking generally, and not specifically taking about a job interview, then "it's important to pay attention to one's appearance" is fine

Hi Flora, my name is Rob. I am a 26-year-old English teacher, originally from the southwest of England. Please let me know if you would like to arrange some initial conversational meetings or lessons with me :) To answer your query - yes, 'look well' is more to do with health - if you 'look well' then you are healthy and not sick, if you are ill then we can say you 'don't look well'. 'Looking good' can describe somebody who has a new haircut or looks attractive or smart at that particular moment. Probably the best options to describe somebody who dresses appropriately for a job interview, etc would be 'looks the part' or 'dresses well' or 'takes care of their appearance'. I hope this helps!

The phrase you use ‘appearances are important’ is good. However, personalizing with ‘you’ is less formal. There are many ways you could phrase this, with an additional question of singular/plural. Studies show that appearance is important for a job seeker. Most people believe that appearances are important for those in the job market. ‘if you want a good job’ is natural, just not as formal, and preferred if you are actually giving advice to someone. There you would have to be careful, though, because there are some elements of having an attractive appearance that aren’t obtainable to everyone. In that case, you might want using narrower words like ‘dress’ and ‘groom’.

Yeah "look well" refers to health. You could say "it's important to look professional" or that "it's important to dress professionally." "Look good" sounds a bit casual for an essay