This origami tech tree shows how most origami skills are related to each other. It also shows which skills are harder, because they use lots of other skills. (This page needs LOTS of pictures, and maybe some animations.)
A few examples, to start off:
... (more complicated techniques) ...
www.folds.net/tutorial (http://www.folds.net/tutorial/index.html) The FOLDS.NET Guide to Paperfolding Instructions on the Web is laid out in the same order as this tech tree, with pictures of the simplest models at the start, and pictures of the most complicated models at the end.
Robert Lang[?]. The Complete Book of Origami: Step-by-Step Instructions in Over 1000 Diagrams. Dover Publications, Mineola, NY. Copyright 1988 by Robert J. Lang. ISBN 0-486-25837-8 (pbk.) Pages 1-30 are an excellent introduction to most of these skills. Each of these 13 models is designed to let you practice one skill several times. Unfortunately, the remaining 24 models leave out lots of pre-creases.
Pureland Skills
Pureland origami[?] can be done by just folding one thing at a time. It has no simultaneous folds a la the squash fold or waterbomb base.
= Fold in half (rectangularly). Unfold. Fold the edges to the centerline.
= Fold in half (diagonally). Unfold. Fold two edges to the centerline. All 3 creases meet at 1 corner.
Simple Skills
= valley fold an "X" and mountain fold a "+", all at the same time.
= valley fold a "+" and mountain fold an "X", all at the same time.
Low Intermediate Skills
= start with a triangular flap with 2 layers (for example, part of a waterbomb base). Make a particular valley fold, unfold, open out, reach in, and flatten. (Some of these "trivial" steps are described on the valley fold page.)
= Start with a triangular flap with 2 layers (e.g., part of a waterbomb base). Make a different particular valley fold, unfold, squash fold, inside reverse fold 2 edges.
Mid-Intermediate Skills
High Intermediate Skills
Complex Skills
Some more detailed notes
External Links
Further Reading