Going modular can be a great way to create a lot of storage with a flexible layout in your apartment. Just start with a single component and multiply as needed:
This is about the easiest approach to "semi-custom" there is. Using multiples of simple furnishings somehow transforms the piece from something basic to something special. This solution can range from inexpensive (as in the first image up top) to pretty pricey (like the system in the second image).
Images: Arthur & Luna, Vitsoe