If possible, always keep the design rights which means you own your design/pattern/instructions and can use them for other purposes. Some contracts (particularly magazines) state once they pay you, they own the design and/or you cannot teach or publish it elsewhere.
Make sure you list basic copyright information on the bottom of each page stating that the instructions are yours and cannot be used without your consent.
Here's an example: Copyright 2012, Kristal Wick. Cannot be reproduced, taught or published without written permission from the author.
- Kristal Wick, Designer, Author, Jewelry Making Expert and Swarovski Ambassador