13. Let's unanimous
When designing her first home, Joanna Gaines made the mistake of giving each room a different theme. One space is nautical miles, and the next is a rustic farm, while the following will be the French countryside. Her guests can tell right away that this is not the top design skill. She learned to go on and make mistakes, so you don't have to. What Joanna left out was the knowledge that you need to have consistency throughout your time.
Earlier on this list, we covered how you need to define your design style. Once you have that in place, there should be consistency across the house. Recall the same color scheme used in every room, as well as the theme. The vibe should be appropriate, as well. So if you want a gentle zen feel in the living room, it should be suitable for the rest of the house.