how much water is in the ocean?

paint it all white
then decide what if anything would improve it.

White is the color inside most refrigerators
Cold, clean, no emotions... do you want your interior to feel that way?

Colored walls (the trick is in choosing the right color) can make design come to its right much better than white. Ask the biggest design retailer ever...

interiors should be based on exteriors. colors should be based on emotions. color theory is such a huge field that i can only offer the thoughts from the top of my head

the PERFECT color
I feel color (applicable to a client I am designing for) is based on the desired feeling and function for the space in question. Involved in the selection are elements of light and texture. I also include (for practicality reasons) the long term liveability of strong colors. For example, orange, while it may be energectic and different, generally people get sick or tired of orange much faster than blue. Sooooo, I would consider painting walls orange rather than purchasing an orange mohair custom sofa.
There are a lot of web sites discussing further the evaluation of color as well as color trend forecasting.

the color of an opinion
as an interior designer that works a great deal in the selection of colors for a room, there are several basic things to look for. the client. what do they do in this room, and what will go in this room. the client will have a feeling for the space and my job is to translate that into the correct shade of gray in the color, how much yellow? is there blue in the red? subtleties. these subtleties are what you should be looking for and in them is the space for your client to feel it works.color. always show more then one color, i prefer three. three greens(or whatever color), one cool, one warm, one grey, and you'll find it easier to come to an agreement as to which is correct for both, you and the client. if you can nail it, the space should look as if it is now the perfect backdrop for the use of the room. look for how much natural light the room gets. as a constant flood of light will affect the room and the color. room lighting. how is it lit? with what kind of bulbs? basically you are creating the flavor of the room. if you have lots of art, you better think of the color of that. how about the couch? what color is that? the curtains. the rug, and on and on....
paint is also just paint and if you think you would love it bright for a few years , then go ahead and be a little colorful for a few years. its only paint and we are only here for a few years.

Why not total black ? I 've been at the New Kartell store in Soho NY and absolutely adored the total blackness of the space. I was a total white fan but when i saw this misture of black walls and colour on furniture i was astonished ,I would never have beleived that black works on walls , i had to see it realised. Better than white !!

this is what female designers think?flashy+ splashy-n- stuff!swirley twirly.

Ahh but we excel in synthesis. Not sure about the swirly twirly part. But we girls sure can accessorize!