Finding your own voice is composed of many things and is, by definition, highly personal. Lyric Kinard has done a lot of speaking/writing/thinking on the subject. She's written a great article in the June/July 2012 issue of Quilting Arts on finding your voice as an artist. Her book, Art + Quilt, imo, is better than Davila's Art Quilt Workbook if finding your voice is a goal (I have taken classes from both Kinard and Davila). Her blog is at
http://lyrickinard.com/blog/ and she teaches three classes at Quilt University, more in person. There's a ton of information online as well, you just have to Google it.
Finding your voice is an evolution, not a sudden revelation. It can include mastery of a technique, developing a certain recognizeable style, the materials or colors you use, and/or even a consistant theme. Think of the artist's whose work you recognize on sight.
The more work you do, the clearer it becomes. Don't be afraid to experiment, to reach past your comfort level. Try every technique that interests you. Learning what doesn't work is just as important as learning what does work. You will recognize your voice...just as you will know each time you get a step closer to it. It can also change, so don't fight it. Look how many voices Picasso had.
I highly recommend you get Art + Quilt. It gives you the art basics, principles and elements, that you need in easily understood terms and exercises and much, much more. See if your library can get it for you before you decide to buy it.
And, btw, in my experience, no class taught by an art quilter has been/will be a duplication of their style...merely an instruction of the technique(s) they have found useful and how you can adapt them to your own work. Then again, maybe I've just been very lucky?