This is the instructional manual for writing spells in verse--however, it doesn't include all the digressions into 101 stuff. Use your favorite books with information on magical herbs, color symbolism and so forth, because this is just about WRITING. (I wrote it, so I should know :) )

This is a good one for referencing the magical uses of stones and metals--important to know if you're creating a charm, amulet or fetish.

I like this one, too--I don't tend to use it quite as much for Word magic, but it's a great reference.

Another of Cunningham's Guides. What I like about these so much is that they are so basic; they provide fundamental information you can adapt to your own practice; you can use these books (and books like these) in conjunction with a "how-to" book that is targeted at a specific skill, and you don't have to get all this same information again and again.