If you have a small apartment, this does not mean that it is bad or uncomfortable because of this. A large apartment full of junk may be smaller than yours. Only the essentials should be present in the decor, you need to get rid of excesses.
It is not necessary to completely abandon massive objects, as they can give an unexpected effect to the interior. For example, a large chandelier gives the room volume.
The apartment needs to reconsider the functionality of the premises. The bedroom can be divided into zones where a dressing room and an office area will fit in perfectly. If there is a room next to the kitchen, you can combine them and get a spacious dining room. The balcony can be freed from trash, and make a small computer room there, but for this you need to electrify it. Of course, you will first have to glaze and insulate a balcony or loggia, the site has a lot of useful information on this topic.
In a small apartment you should use every corner. For example, in the hallway or corridor, you can make a mezzanine. But this is only possible if the apartment has high ceilings. Do not forget about the corners, they also need to be filled. In the corner, you can construct a podium where you can put anything, even a bed.
To visually enlarge adjacent rooms, it is recommended to paint the walls with uniform colors and use a single floor covering. Floor and ceiling mirrors also visually enlarge the room.
Dark colors add richness and depth without narrowing the space at all. So it is not necessary to use only light colors in the interior of small apartments, you can experiment and add dark colors, or something bright, saturated. It is important to know that the room seems low when the ceiling is darker than the walls. It is also not recommended to use the same color for walls and ceilings.
As for lighting, if the room is low, a central chandelier is not recommended. You can replace it with local lamps that will give comfort to the room.