Don't assume any white wall will do. Both the quality of the paint and the tone are really important. Choose a white the same way you would any color - by getting paint chips and looking at them in differing light conditions through out the day. Don't make a decision too quickly, you'll be happy you took your time! In terms of quality I am a big fan of Dunn Edwards. But I also think Frazee paint is really good too. And I've had some success with the Martha Stewart paints and Sherwin Williams.
2. One way to do white is to keep almost everything white - white furniture, white accessories for nearly everything and then adding just a smidge of color as in here with the pastel lights and the yellow artwork.
You can choose a "white" that has a smidge of color in it - gray, pink, blue, green - it will still be white, but under certain light conditions the slight hue of color will be noticed. This white is really white with a drop of gray.
White works well in a room with lots of different textures going on - the wood floors, the textiles, the lamp, the wire fixture, these things all give heft to the space. And the paintings in this room are great with the colors they add.
Keep everything - even your colors super neutral as well. This really gives a restful and cohesive feeling. The biggest problem I usually see in white walled rooms are where no thought has been giving to the mixing of bold colors and pastels and neutrals - just because the walls are white doesn't mean everything should suddenly be thrown together. It still needs to be a pulled together look.
Keeping all the additional art work and furniture to basically one bold color works really really well as you can see in this room with the green furniture.
Art work, art work, art work! I saw this all the time, but it's the best way to make a room really look fantastic. Smartly here they've kept the art to a neutral-ish palette which is in keeping with the feeling of the space and the feel of the eclectic wood table and chairs.
This is from Reese Witherspoons Ojai California home (I know aren't you jelly?) - nary a pop of color to be had in this room which makes it feels so earthy and restful.
If you're going to add a pastel color is is perfectly fine to add one or two more. Because they are all so subdued, they all work well together while keeping it as a cohesive concept.
Bold artwork makes the room work well here.
Attention to detail is important. Keep things from being cluttered - be thoughtful about what you choose as accessories. It's the biggest reason rooms end up looking "decorated". It's the editing that ends up being more important than almost anything - and it's sometimes the hardest thing to do.
Doing something trendy like hot pink and orange (very on trend at the moment) works really well in an all white room with tons of white background - as in this room where the headboard, bedspread, lamp and mirrored side table keep everything super serene with this boldness added.
Lots of bold with some black - but with the white table and the white bend it still looks really good together.
so carefully edited so that you just notice everything that is great - the light fixture and the chairs are the focus here.
Go as bold as you want and add as much color as you like once you've reached the basic white background - here, couch, carpet, walls and tables are all white allowing the ability to add as much crazy color as needed. The result still looks really pulled together and chic.