You know the people that always crush the exams and can charm the pants off anyone?
Be better than them.
This is basically all you need to know.
--In terms of Step 1, the higher your score, the better. Although scoring above a certain number may make you more competitive to match into
any derm spot, a higher score will only help you.
--Be outgoing, charming, likable, and understand that appearance matters. Some people may think the last comment is stereotypical of derm, and to some extent it's true, but in any profession (law, business, or other fields of medicine) someone who dresses well and is well groomed looks more professional. If you are a woman, make sure your hair, makeup, and nails are done tastefully. If you are a man, make sure your facial hair is well groomed, your pants are tailored, and wear a non-ugly tie (these are random points, but most men in my med school seem to be repeat offenders when it comes to these three).
--Research is important for several reasons. Not only does it give you academic credibility, but it is a great way to form a close relationship with a dermatologist who can write you a great LOR for residency. There is also a ton of incidental learning involved in research, and random pearls you learn will make you look smarter than you actually are when you are on aways (you have to do this in the right way though so you don't look like a pompous know-it-all).
--Taking a year off to do a research fellowship is becoming more and more common. It will not hurt you, but YMMV
--Derm is a small field, and interviews are VERY regional. Also, coming from a top school will greatly impact where you receive interviews
--There really are no bad programs, but some are better than others (however, what constitutes a "good" program is highly dependent on what type of training one is looking for)
--AOA helps a lot. There have been posters in the past who remarked on this, but at several interviews, my interviewers had my ERAS picture along with my Step 1 score and AOA status. FWIW, last year, over half of all people who matched to derm were AOA (the highest of any specialty).
--You will be compared to other people in your class who apply for derm. If there are only 2-5 of you, it shouldn't be too bad, but many, many schools have 8, 9 or 10 or more people who apply to derm. Supposedly this year Harvard had 15+ applicants, and as a result, they were unable to offer interviews to all of their home students because they would have taken up too many interview spots.
--Do not ever say negative things about other people in derm because given how small the field is, they may come around to bite you in the butt. Also, never be a gunner or throw your classmates under the bus. Again, things will come around to bite you in the butt. You do not want people to remember you as "that gunner gal who screwed people over so she could match into derm." Instead, you want to be remembered as "that classmate of mine who was super nice to everyone and easy to get alone with. I am so happy that she was able to get a derm spot!"
--Try to get to know the faculty in your department, but understanding that at MOST med schools, derm departments are not super friendly to med students. Be persistent and do not get discouraged.
--Don't tell people you want to go into derm: people will assume you're probably going to try to screw them over