I use thin muslin foundations, it makes life much, much easier.
The BEST info I've come across is from Allie Aller and Sharon Boggon.
Allie Aller's book is worth every penny. Tons and tons of tips with good step by step pictures. Plus beautiful pictures of finished crazy quilt projects.
Sharon Boggon shares a multi-part tutorial on her blog showing how she created her diamond crazy quilt. Just like in Allie's book, this set of tutorials is also very in depth and excellent.
Sharon also published a book on crazy quilting but I haven't purchased it yet.
Marsha Michler has several books on crazy quilting.
I have this one and like it very much. But if you're only going to buy one then I highly recommend Allie Aller's instead.
I've had a blast since taking up crazy quilting!! I love to hand embroider the seams but using the fancy stitches on your machine will also turn out fantastic.