1) Comfortable CAN be fashionable. I will be the first person to break out the stilettos, however squeezing your toes into 6 inch pointy heels may not be the best idea for a 14 hour flight. Wear clothes that are functional and cute. For example: leggings can be one of the most comfortable bottoms. Pair them with a cute top, a blazer, and a cashmere wrap, voila! You look put together but you are also ready to catch a few hours of sleep if needed.
2) Pack for you and your destination. Whenever you are going somewhere you need to keep in mind, you are still YOU! Don't bring clothes that you would never wear at home just because you think you'll suddenly want to wear a leopard print bodysuit on a trip to San Francisco. Also keep in mind the reason you are traveling. Is it a beach vacation? Because then you should probably leave the parka at home.
3) Know how to pack your clothes. If you have items with delicate beadwork put them in cloth muslin bags, wrap them in tissue paper, or don't bring them. Shoes that are suede or velvet should also be put into bags. Jewelry, should be in separate mesh drawstring bags, or buy a travel jewelry box. (The one i have was affordable and is FANTASTIC)
4) Don't forget the basics. Bras, every type of underwear, camisoles, spandex, bandeaus, lingerie tape, petals and pasties. (Lingerie tape and petals can be found at most dollar stores)
5) Make your packing fun! Invite some friends over, open a bottle of anything, put some music on and have a fashion show. You should always try on outfits before packing them so why not make it fun and bond with your friends before you leave?