1. Start on time
2. Wear heavy clothes on the plane
This is a really easy way to make your suitcase lighter. Wear thick clothes and heavy shoes on the plane or wear layers, everything you wear doesn't have to suit in your suitcase anymore. Especially when you want to bring a hat it's a must to already wear it.
3. Set a limit
Everybody wants to bring as much shoes or other stuff on vacation, in case of. But it's a good idea to set a limit. Maximum 3 pieces of all is recommended so you don't take 5 jackets and 6 shoes in your suitcase you don't wear.
4. Choose your outfits in advance.
The best tip is to choose your outfits at home. Choose what you're gonna wear at home and take a picture of it. By this tip you don't have too many clothes in your suitcase you don't wear and it saves time on vacation. But if you don't like this way because you like to choose at the moment there's tip 5
5. Take basic stuff with you
When you take basic stuff with you it's easy to combine. If you take a basic short almost every top/blouse fits at it. Make also sure it fits at your jeans or skirt. By this way you can easily combine on vacation depending on your mood.
6. Roll your clothes
7. Put your socks in your shoes
8. Make choices!
This one is probably the most important one. You can't take everything with you so make choices.