( photos are a bit dark…sorry)
First step…the drawing in fine liner pens- 0.05 width on rag paper, then start with your lighting and where the light hits the walls and curtains…those will always be lighter.
Next, fill in colour, consider shading and where your light source is coming from. Then…leave some whites! Don’t get carried away with filling all of the space…breathing space is important! Also, items have thickness, and cast hard shadows, so be brave! Bold contrast and colour make the best renderings!
Lastly, use shadowing, cross-hatching, dots and folds to mimic fabric types. Lastly, sheen on floors and a .5 fine liner for lines between shadows and objects. Sign! Scan! Post!
Enjoy…let me know how if this brings you back to the drawing table :)