I never did master quilting on my DSM. I only have one quilt I did that I'm actually happy with, and it was a fairly small wallhanging.
After I got my longarm, I tried several different styles and found that pantos were the easiest and most successful for me. I haven't had it for very long, so I'm being patient with myself before I dig into custom FMQ.
I looked at everything I could get my hands on and quite honestly found videos to be much more instructional and helpful than books. There are so many free videos on YouTube.
You don't say if you're quilting on a longarm or DSM, but there are helpful videos for both methods.