The most common tip for a small and dark room is to go for the white look. White makes a room look bigger and it feels clean and light.
But, in a room where there’s not a lot of light coming in, white can look a bit bland. So unless it is executed perfectly, a light colour is maybe a safer solution (if you want to go for the light look). But you can also go bold and choose a very bright popping colour that will make the room look warm but not cramped/small (or of course a combination as pictured above, white base but furniture in popping colours).
Another tip: Don’t put too much furniture in a small room it will make it look even smaller and more cluttered. Pay close attention to good lightning in a dark room. Also you can use mirrors that will reflect the light that is coming in to the room. Also mirrors will make a room look bigger!