For small items, like g-strings or thongs, you can zip them safely in makeup bags (without makeup of course) to keep them all together and collected. A quick shake will put them back into the right shape. For bigger items, like your bras or your negligees, you should roll them so there are no creases, making sure to hook the bra so it doesn’t catch or snag on anything in your luggage.
Remember that your luggage may be searched, so you want to make sure that you are packing everything in the right way, perhaps using clear plastic bags with labels that allow the luggage handlers to see everything but keeping them all clean and sorted. You are also protected if there is a problem like your luggage pops open on the baggage carousel and all of your lingerie comes popping out. (You ever notice that it is only your bras and panties that strew themselves about like that?)
Toss in an extra plastic bag for dirty lingerie when you are packing to return home, keeping in mind the same keys that you used when packing. You may also find new lingerie while you are away, so always pack a little extra room or consider tossing some of the old lingerie to make room for the new. You know the old saying “out with the old, in with the new”.
Finally, keep in mind that you should count the lingerie that you are wearing for your trip while you are packing so that you can keep track of how many of each item you are taking and how many you are bringing back.