A color theme (scheme) with a lot of colors is tricky to manage and will often make the design look too busy. But just few colors can make the design look boring and unattractive. However, I have seen masterful designs using only two or three colors.

Try to make your design decision, with only three colors.

Three color combinations is a good starting point for room design. Three colors is enough to create variation and visual interest. A three color theme is, where the colors are equally spaced around the color circle. This is a good choice for basics, because it is easy to get good results. A split complimentary color theme is another good choice.

Design your Kitchen, Bathroom with "60 - 30 - 10" rule for success.
60-30-10 splits in between three colors: one color on a majority of the space, a little bit less of another, and an even smaller amount as an accent color. In the kitchen, for example, your primary color might cover the walls or the cabinets; your secondary color would be floor; and your accent color (texture) will be countertops.

When designing a particular room, divide your three colors into percentages:

60% of a Primary (dominant) color
30% of a secondary color
10% of an accent color
Natural Stone, most likely contain a lot of colors in it. This is especially true of Slates and some Granite. In such cases, it is quite allowable to draw the colors for the room from the palette of colors represented in the stone. Then, it is the stone that serves as the harmonizing factor in the room, and thus is becomes the focal point.