First of all, congratulations on getting accepted to medical school.
I'm not sure what you mean by "specialist of equal popularity", but I will do the best I can to field your question.
First of all, residencies in area such as Dermatology and Opthalmology are difficult to come by. Although grades and boards scores for the majority of residencies are indeed important, they are ESPECIALLY important for these areas.
You will need to do well in school and on the boards, as well as have some great recommendations from your clinical years. I know of several PCOMers who have gone into these two specialties over the last few years and all of them were very strong academically.
SO, the keys to success would be...
1. Great grades...better than average for sure
2. Great board scores...again, better than average
3. Find a mentor...preferably someone with a "name" in dermatology
4. Acquaint yourself with dermatology programs...try to do a rotation at the same facility...certainly a dermatology elective at the place you are interested in
5. Try and have something "special" on your transcript...research, etc.
Good luck