The first part of my answer is, when crossdressing, I dress so that I feel my outfit is appropriate for who I am. Now, not that I'm delusional or anything, but personality/developmental wise, I'm kind of stuck self identifying as a young teen girl. So most of what I wear are things that represent that feeling. I don't go out crossdressed, and pretty much never look in the mirror, so take that for what it's worth.
Now, on who other people dress for. Women will deny they ever dress 'for' other women. Yet, no men give a rat's ass about designer names on clothes. Yet, a whole lot of women go to great lengths to buy designer name clothes and let other people know about it, either by displaying the designer's logo or making sure they mention it casually in discussion. I think that a lot of women DO dress in ways to make a statement, whether that statement is about sexual desirability, class, wealth, fashion knowledge and being up to date on what's currently in style, or in some cases, to show off jewelry that other people (usually men) have paid a lot of money for her to wear, to demonstrate her desirability to that man or men, perhaps to let everyone else know how much she is valued by the opposite sex. If there are any questions about whether people dress for others, perhaps compare what they wear in their own house when no one else is home or coming over, to how they appear when in public. I think in 99% of the cases, you'll find two completely different appearances. So the idea that women only dress for themselves is nonsense; when they know they'll be seen by other people, they always make an effort to look better than, say, when they're staying at home late at night alone, doing the laundry, which is when they are truly only dressing for themselves.