In the end it doesn't matter, what happens after they get taken off is what guys really care about
You can get bonus sexy points for sure though by having cool underwear. I love seeing girls thongs at college, makes walking between classes so much better.
Black underwear is sometimes said to mean the girl likes/wants/dressed for sex, so that's a good color to fall back on I guess
Pink is the girliest color imaginable too, so can't really go wrong there. Sometimes girls who are too girly are really offsetting though (usually bitches/stuck up) and a lot of pink sometimes gives me that impression (it just reminds me of a barbie doll). It might be wrong of me to think this (I should look up if it's been answered) but other guys might inherently think that sh*t too I guess.
I dig lacy stuff too, not even necessarily lingerie, fancy panties do the trick. Not every guy cares though, but obviously it's not just me (playboy has plenty of lingerie issues so there's demand out there).
I really don't think matching is something guys even think about, unless the dude works in the fashion industry or something. If your panties had a smiley face and your bra was some victoria secret thing, I wouldn't give two halves of a sh*t, I'd just keep undressing you.
So yeah in the end it's really not even on a guy's list of things we really look for, it's just something we notice from time to time if what you got hit the spot. Don't worry too much about it. If you ever want to know for sure just ask your boyfriend, he might even take you to victorias secret and buy you what he wants to see on you (always a blast if we have the money).
It's sort of like a cherry on top: I'll never complain about a bowl of ice cream, but it's even better with a cherry on top. So you don't need to match them or wear anything fancy or colorful to turn a guy on, but if you do wear that, then he'll get even more turned on. At least in my opinion, anyway.
Love matching, patterns are okay but don't overdo it. Styles, well depends on what your planning on wearing, but I love girlie colors, pinks, light greends, light blues, but its mostly how you wear it. If you feel sexy in it, your look will appear 100 times more sexy.
It tells you about him and him about you if you think about it. If he doesn't care about what kind you wear as much he is probably only wanting sex and just wants to get them off as fast as possible. The style of them also tells about your personality in allot of cases. It may not be true for everybody but the less material the racier and more outgoing she will be. If she is wearing fuller cut panties she is more likely to be laid back and easier going. Also for some guys its a turn off seeing to much too soon.
If things have progressed to that point, the underthings involved are not going to matter much; and if you're looking to appeal to a particular guy, it'll pretty much depend entirely on his tastes/the theme of things.
I'd say that, like any outfit, so long as you look good in it, and it's not entirely pedestrian (you are prancing around in skimpy things, after all), it'll be fine.
I do prefer that they match/go well together, and a bit of lace never hurt. Also, front-clasping bras make for easier removal, and I've been told that they're more comfortable. *Shrug*
From personal experiences, guys find boyshorts sexy (especially in black or pink)... they also like laced bra's with matching underwear. Other then that.. wear anything you find comfortable and that you think you'll look sexy in.