We are repainting the exterior of our house--just the eaves and fascia (rest is brick, not painted). Old paint is in terrible condition--flaking badly. So we are scraping, then sanding a bit. Then...do we caulk first, or do we prime first and then caulk? I kind of think priming first would be better so the caulk has a better surface to stick to, but I am new to this. Tips appreciated.