The level, type and direction of lighting can all affect the tone of a paint colour once applied to a surface and can vary significantly compared to sample cards. Identifying each of these is the first step when considering which paint colour to choose and also which paint finish is best.
Identify the level of light available, is it darker or light? Of the available light, is it natural light coming through from windows or artificial light from ceiling lights or lamps. Then it's a good idea to look at how this light changes depending on the direction of the space at different times of the day - north, south, east or west facing.
Once you've identified available lighting, it's easier to narrow down which shades and tones work best within the space. You can also then look at which finishes will be best to enhance or leverage available lighting such as matte, low sheen or gloss.