Interview for first sales job Monday

I'm 25 and just got off the phone with a roofing company and have an interview with them tomorrow. I definitely didn't lie, but I didn't really let off how little I know about sales or roofs lol. Any advice on how to prepare? Videos, articles, key questions for the interview etc. It's also my first professional job as I am currently a Bartender and was a paramedic before that so even very basic stuff like how I should dress would be helpful (is a nice dress shirt and slacks enough? Should I wear a tie? Full suit?) Also it's a door to door sales position and I am wondering if that's a red flag I imagine that's pretty normal for roofing sales, but I know very little about the industry. Any advice at all would be greatly appreciated. TIA