Pictures from "How to Make a Paper Ninja Star"
This isn't qualified as an "origami creation" in my book, but just a tutorial on how to make A4 paper into a square, as it is required in many of my instructables.
You will need:
Step 1: Fold the Corner
Turn the paper horizontally. Take the top left corner of the paper and bring the whole vertical side onto the bottom side and fold.
Step 2: Cut the End Off
Take the scissors. Cut along the right edge of the triangle fold from before so the end gets cut off.