Here are some suggestions to help ensure that your clothes survive the trip.
Check the zippers, buttons, seams etc., of all the clothes you're going to pack. Make sure they're in good repair.
Put plastic garbage bags on the bottom of the suitcase and between different layers to reduce wrinkling. They're also great organizers while abroad.
Stuff socks into your shoes and put the shoes in a plastic or cloth bag.
Roll up undergarments and fit them into the corners of the suitcase.
Place the heaviest things on the bottom of your bag such as shoes, belts and books. Follow that with jeans, sweaters, heavy skirts, sweatshirts, etc. Next add light but bulkier items like dresses, jackets, light skirts, sport shirts, blouses. Follow with wrinkle-prone, light items.
Do a trial pack. Weigh your suitcase(s). Twenty pounds should be the maximum. If it's heavy now, it will feel three times heavier by the end of a long journey. Streamline before you go.
A space saving idea from backpackers is to roll your clothes into neat cylinders with layers of plastic or tissue paper in between. This works well in suitcases, since you will end up with a lot of tight rolls that fit together well. If you roll several items together, you will end up with less wrinkles.