Here is a tip for gaining the correct perspective in your sets. First and foremost remember that items closest to you are larger in proportion to the items at the back of the room.
Let's start at the back of the room: This empty room has no doors. I added one. I guessed at how big it should be. That determines how tall the wall is. Shrinking the door on this wall would mean we had very tall walls. I pulled Barbie into the set and guessed at how tall she would be in proportion to the door. You use them every day, so you can kind of guess how tall you are in proportion to a door. Make Barbie that height.
Then I pulled in a chair. I made the chair proportionate to Barbie. usually the seat is somewhere around your knees on a average chair. It could be just below or above depending on your height.
Now to the center of the room. This Barbie is taller than the first Barbie, but the tops of their heads are at the same height. This is because - no matter where you stand in a room you will always be the same height. The pink bar illustrates the fact that all three Barbies are at the same head height. As Barbie increases in size so did the chair. Making the chair closest to the front of the room the biggest.
I've grown up working with perspective. I can eyeball it pretty good. However, there are times that I need a little help. When that happens I grab Barbie and let her help me to size my furniture to fit my room. I do exactly what you see here without the pink bar. I set whatever item I intend to use in the back of the room at the height I think it should be. Then size a Barbie next to it. Then I place a Barbie where ever I am having trouble with perspective and stretch her till the top of her head is at the same height as the smaller one. Then I can make the furniture I'm having trouble with proportionate to the bigger Barbie. Easy!