Designing a small space is just like designing any space. first you should look for unity in two ways
first, The Scale. Scale of Furniture and decors must have same size and the of the things in relation of the space itself.
Different pieces must have applicable size to each other. Choose a right size not too big nor too small. we Don’t want a big couch stuffed in a small space.
next is Aesthetics, We want all to be “fit” visually, But don’t match, Matching can build a boring and unsuitable effect.
Considering that aesthetics creates a singular look in unity, aside from getting mixed and matches.