Teefury

So I've been teaching myself Photoshop on and off for years through tutorials I find online. Recently I've been helping my student organizations out by designing T-shirts for silk-screening and I've found that printers prefer art submitted through Adobe Illustrator. Every attempt so far to get started teaching myself Illustrator has ended in frustration and confusion.

Does anyone out there know a good starting point for learning Illustrator? A specific site, tutorial, or book would help exponentially.

Thanks!