Some random advice I can give from my experience modeling Andy's room: First, decide how much you really need. Assuming you want it to look good from every angle, the first problem you'll quickly find is that its hard to see what your doing. My solution to this is to do the following.
Make your wall, floor and ceiling materials double sided with the back faces transparent. This lets you see inside at all times even though your on the other side.
Make sure your faces are inverted or else it wont get lit properly.
make the ceiling a separate object. this allows you to keep it hidden when modeling to more easily select various props form the top view. also, I'd suggest not keeping the ceiling a paper thin face. shell it a bit
Once you have placed enough props/furniture you should start to have enough to allow you to work blind. as is when you hide the walls/floor mesh while fleshing out other details.
I usually try to model props in a separate object, but copy/paste them into the main object later for adjustments. Its definitely a good idea to see what they look like inside the room first, as opposed to just adding it in scene mode. This allows you to keep scale in perspective while deciding the size of things. Ive tried doing every prop as a separate object in scene mode and its just a mess as far as scale. Try to have some kind of reference point, maybe even a stand in for a human so you know what how large you want things to be. Scale is one of the most important things for a room to feel right. It takes a lot of fine tuning and constant adjusting.
the perspective view in can be useful in modeling mode, just make sure you make the room a good size for it. make it too small and it'll be hard to keep its axis centered, make it too big and it'll clip the camera a lot causing a lot of distortion.
