The 0rigami basics shown here are the backbone of origami folding. Many origami use these basic techniques and many instructions refer to these terminology here, so if you have an understanding of the basics, you'll be able to understand many of the instructions.
First are the different type of folds. Here you will see the Basic Origami Folds used in many origami.
Below are the origami bases that are the beginning point of many models. If you run into instructions that tell you to begin with a certain base, you can learn how to fold the base here.