)
@Blima-Spetner it's really hard to see your picture and I am no expert. Though I can relate! The first several times I did this it was pretty hard. I think making a grid is a good place to start though and then establishing the room.
I usually from a perspective viewpoint draw the squares for the furniture on the floor first so that they are in the right place next to each other. Then build them up into the combination of cubes needed to make them the right hight.
I think drawing traditionally might be harder because things are not easily sized up and sized down. If your grid squares are too big on your piece of paper things don't fit as well. And too small can make it hard to work.
Perhaps a good idea to get a hang of what size squares you need for your grid is to just draw a few different grids on several pieces of paper. Put a a few small boxes in them along with the edges where you will put your walls. see how the samples look in the space you have available. Once you feel confident you have the proportional size and viewpoint you need for your picture. Draw in the boxes for the room. It might take a few times to get it right.
Doing a grid and working on a single object in a room could also be helpful before diving into the whole thing. Just to get a hang of drawing from grids and boxes, which can feel incredibly unnatural haha.
I am sure there are lots of ways to go about building this room however, so I think expirimentation will help you find the way that works best for you 