Okay, a lot of notes for the origami initiate.

Creasing and Precision

The key to pristine, clean models is simply being careful with your folds. However, there are some tricks that you pick up over time that go beyond perfectly square angles and exact centers, and the only way to master them is practice. A good teacher helps too.

One thing I’ve noticed is that if you’re folding a model with several layers the paper tends to “creep” because the folds and creases distort it; always keep in mind that some diagrams don’t depict the paper’s behavior exactly. Check and make sure the edge of your paper is where it’s supposed to be before you crease. The degree to which your paper creeps depends on the amount of folds in your model, but also on the type of paper.

Types of Paper

• Traditional, Woven: these are the squares with the interesting textures and the overtly Japanese patterns. They’re thicker and stronger than other papers, harder to crease, and should probably be used for the final model. If you’re starting a model you’ve never folded before, it’s best to practice on cheaper, easier paper first and then fold the final in the good stuff. Good for wet folding.
• Glossy, smooth: this paper is thin and colorful, creases easily, and is sold in a myriad of sizes, patterns and colors. Doesn’t react well to water, the colors run. Good for modular origami where you need a lot of paper that’s exactly the same size.
• 8.5”x11” letter size white printer: Good for everything. Easiest thing in the world to practice with and if you screw up it just becomes scratch paper.
• Foil: You can buy specialty packs of metallic origami squares for making ornaments or pretty cards or whatever. I don’t know if they sell foiled paper, which would be easier to work with, but in the past I’ve encountered squares of very thin, colored foil. This stuff is tricky to work with because it doesn’t curve smoothly like regular paper does when you fold it, which can mess up the placement of your ceases. Would not recommend for beginners. No grain to speak of.
• Tissue or Tracing: The smaller you make your models the thinner your paper has to be, especially for models with many folds. Using tissue or tracing paper reduces the creep in smaller models with many folds, but it is much more delicate.
• Newsprint, Magazines or Wrapping: For making interesting boxes and gifts, these are good choices. They’re generally thin and crease well, but remember that models made from these are probably best suited as ornaments because they’re not very strong. Wrapping paper comes in a wider variety of thicknesses, but nowadays often has a grid of inches printed on the back, making sizing easy-peasy.

Grain

In some models the grain of the paper is very important; the grain is a characteristic of how the paper was made and it affects how well a piece of paper will fold or curl in one direction or the perpendicular. Diagrams where the grain is relevant will probably tell you; I know that if you’re making a jumping frog and it doesn’t seem to snap very well, it’s probably because the grain is oriented the wrong way.

Dimensions

A good set of instructions will always give you the dimensions for the paper you fold your model with. Conventional origami usually requires a perfect square, but there are whole genres that specialize in folding irregular dimensions. Some require a dollar bill, but if you’ve ever actually measured a dollar bill it comes out to about 6.1”x2.6”. That ratio is roughly equivalent to 7:3, which means that you can use any rectangle with that ratio to practice dollar bill folds on a larger scale.

When sizing your paper the easiest and most accurate method is to crease well and tear, but if you have a straight edge paper cutter (such as for scrapbooking) those work well too. Scissors tend to wobble, and while uneven edges aren’t a problem for some models, they can throw off the placement of your folds.

Key

Always pay close attention to the directions in your specific diagram, but I think these are pretty standard. Some of the best diagrams are in different languages, but if you know how to interpret the pictures you can get by anyway.

• Dashed lines (- - - - -) valley fold: the crease points away from you, or down
• Dash-Dot lines (-·-·-·-·-) mountain fold: the crease points toward you, or up
• Solid lines (⎯⎯⎯): edge of the paper, or folded edge
• Dotted lines (■■■■■■■■), or lines with scissor icon (✄): cut
• Solid dots (•): pivot a fold on this point
• Empty Dots (o): bring these points together
• Arrows, sometimes curved: flip or rotate model this way; sometimes flip only one part of the model (see the next picture in the sequence to check)

Preliminary Folds

Sometimes a diagram will start from a simple fold that they expect you to know, sometimes called a base; here’s a few:

• Square
• Waterbomb
• Fish
• Bird
• Kite

This site has 15 bases with good diagrams.