Wallpaper, like paint, can add charisma and personality to a home. But if you are sprucing up a home on a budget, hiring a wallpaper contractor might not be at the top of your list or budget, and DIY-ing parts of the process might be a better choice. 

Unless you’re an industry vet, knowing every design rule is hard. It’s even harder to follow them all, whether or not you’re a pro. Still, there are always going to be things that designers simply can’t ignore when they walk into your home—and unfortunately, some of them cost a pretty penny. Below, five designers spill the six expensive decorating mistakes that make them cringe the most.