Current derm resident.
Basics are needed of course - good foundation of knowledge, procedural skills (biopsies, excisions, since these are where you'll be doing a lot of your billing), empathy, bedside manner, etc.
Perks - Business savvy, understanding of how to code and bill properly, or just a good business partner/group
Derm is "high-procedure" in the since that you biopsy a lot and if you like the surgical side, you can choose to do a lot of your own excisions or procedures (vs. sending out to surgery, plastics, etc.). Other samples of "procedures" that you bill for beyond the basic office visit - cryotherapy, intralesional steroid injections, acne surgery, etc. Alternatively, you can also choose to do very few procedures and still have a viable, but likely lower-income, private practice.