Tip 1: If you are selecting the color form the COMMON textures, try Basic color 25. (Search v25). Not only is it white but also has an appearance attribute of flat paint so it doesn't reflect adjacent colors as much as the higher gloss finishes.
Tip 2: If you are using lighting from the ROOM_FUR catalog, double-check the properties. For example the SPOT.RECESSED light defaults to a light yellow color. You can change that to white. (Right-click>light properties>color dropdown).
Tip 3: If you add a light source from the ROOM_FUR catalog, it will add light to your space without the actual need for a fixture. Generally you can always select Omnidirectional Light Source but there is also one that is set to shine up or down. Below is the example of a fixture from SketchUp or the Cloud Browser + Omnidirection light.
Tip 4: When you are ready to render, adjust your Light Effects Launch High Quality rendering (camera in the dashboard) and then revisit the Light Effects to adjust the exposure.