This site has excellent step-by-step pictorial instructions for making elf ears.
Link: http://zeldaness.deviantart.com/art/How-to-Make-Costume-Elf-Ears-135064150
This site has some good basic instructions for putting together a homemade elf costume for your child.
Link: http://costumepop.com/how-to-make-costumes/how-to-make-an-elf-costume/
Here is a site with patterns for making a number of different elf costumes.
Link: http://costumes.lovetoknow.com/Patterns_for_Elf_Costume
