If I could only give one piece of beauty advice, it would be this: Visit your dermatologist. Your friendly derm is the key to solving every skin issue you could possibly have — whether it's flakes, pimples, dark spots, or anything else. And since good skin care is the basis of good makeup application, it's an investment in the foundation of the house that is your beauty routine.Despite my chest-pounding declarations of the magic of dermatology, there are still plenty of people out there who don't take advantage. I can understand that: You're busy, you're managing your acne just fine with over-the-counter cures, and it's one more appointment to add to your already packed calendar. But there may be another reason that's holding you back: Derm visits are different from other doctor visits, and can seem a little daunting.Well, that's where we come in. We chatted with two top dermatologists — Sejal Shah, MD , and Ted Lain, MD — about everything you need to know before your first visit. From what to bring to how to figure out your insurance, here's how to make sure your first appointment goes swimmingly.