Here is the question I hear most from new collectors, usually standing in my shop with a piece in each hand: "I love this 1970s lamp, and I love this 1950s chair — but if I put them in the same room, won't it just look… random?" I understand the worry. Most of us did not start with a plan. We started with Grandma's dishes, a chair nobody else wanted, and one irresistible estate sale find at a time. So the house fills up with lovely pieces from six different decades, and one day you look around and think: collected, or just cluttered? A room full of one decade can feel like a time capsule you are afraid to sit in. A room of many decades done carelessly can feel like a flea market booth. And if your taste runs to a cozy cottagecore home, or full grandmacore like mine, you already know the pieces are never going to come from just one decade. The good news is that the difference between the two is not the pieces. It is a handful of simple rules — and once you know them,...