I've added the skirting board, adjusted the borders and the colour of the main wall. Though it has been suggested to add a poster to the back wall, I do not want it to be overpowering the educational posters that are already on those walls so I've added a bit of texture to it but it doesn't seem to take effect. Hence, I will try bump mapping it to give a more realistic feel. Apart from that, I was thinking of adding a couple more poster to the left wall (by the window) as the space there seems a little bit empty. In addition to the further enhance this set, I've done some adjustments in terms of adding folds onto the posters. However, it still looks unrealistic. The lack of shadow might be a contributing factor to this problem.
In comparison to my previous shot, this looks better but I am not satisfied with the overall look as it still looks too CG. I will further enhance the scene by fiddling with my lighting set up and I have decided that this will take place at evening time where the light from the outside world would not affect the scene as much except giving some rim lighting to the top of the bookshelf and the edge of the table.