Personally, I think a man can wear womens' clothing items without cross-dressing. I think it's a little ignorant to say that women can wear whatever they want and not be cross-dressing, but if a man wears an overtly feminine clothing item, he is cross-dressing. I almost always buy womens' jeans and dress pants instead of mens, because they are way cheaper and fit a lot better, I buy womens' blazers, and sometimes womens' shirts.
Mens' clothing is so boring in most retail stores. I think it's absurd that women get all these cool, totally different aesthetics that they can apply to themselves, but men only get one. Finding something even remotely androgynous in the mens' section of any store in your local mall is ridiculously difficult.
Also, I used to wear makeup a lot, especially when I would go out for a diner party or event.

All that being said, I'm very good at it, and I pull it off when I want to. The thing is, if you want to look good and not freaky as hell doing it (like the guy in the video a few posts back), you need to put in the same effort that a woman does when she wears these clothing items. So yeah, you need to shave the armpits. Can you imagine a woman walking around with hairy armpits and a strapless dress on!? And yes, you need to learn how to do makeup.
A side note, most of the people you see cross-dressing who just look terrible, those are people who do it as a fetish. It's a sex thing for them, and actually people get off on how they look, believe it or not.