Color is a powerful way to communicate, because colors affect people emotionally and influence their moods.
See these slides on the psychology of color:
Try to think what your color scheme communicates, what mood it sets. More important than the dominant color (reds, greens, blues, etc.) is, in my opinion, the boldness of the color scheme you use. Do you go for muted colors, or for bold, high contrast ones? What kind of color scheme can you choose to make your presentation “pop” and communicate confidence? I, for one, don’t like the muted, elegant, dainty color schemes that mix beiges and greens (yawn). I prefer strong, high contrast colors, but still ones that go well together in a color scheme.