Choosing the right colour for painting?

I have painted my unit 4 or 5 times in the last 5 years, and am never happy with my choices! i have a open plan unit which combines living room, dining room and kitchen. I have light wood flooring with a beige lounge. I wanted one colour for a feature wall and another colour to form the principal colours. My kitchen has light green cupboards and the benchtops are a dark grey granite. Has anyone any ideas, ive tried greens, a blue, some browny colours, nothing seems to work