Where are you going? What are you gonna be doing? Have you met the guy before or is it a blind date? If you've met him, what were you wearing? "Dress to impress" is very open ended, it all depends on the situation.
really depends where your going and if you've met the guy before ect.
Usually, if I know we are going for coffee or something relaxed or I haven't met the guy before, I'll wear a nice dress. Do my hair and make-up (hair and make-up is always ALWAYS the same for me, no matter the occasion). Make myself look presentable.
If I know the guy or were going somewhere active like bowling, I wear jeans and a cute top. with hair and make up, and still looking presentable.
I think the key is to be comfortable, as first dates are always awkward.
and make sure you look presentable.