"The words we say to others account for less than 10% of first impressions."
Naturalist Charles Darwin -- yes, that Darwin -- first launched the study of nonverbal communication when he published The Expression of the Emotions in Man and Animals in 1872. Today researchers believe that we make first impressions of people based on three factors: body language, vocal delivery, and the content of what we say.
Although statistics tend to vary a few percentage points here and there, what we say accounts for just 7% of that first impression, vocal delivery (tone, pacing, etc) accounts for 38%, while body language accounts for the rest -- a whopping 55%, something to remember when approaching a woman for the first time.