I read Tristan Taoramino's book, and I'm pretty sure my husband did some of his own reading for my training. As I've said before, it took about a month of training before I felt comfortable enough and was able to relax the muscles enough to achieve what we wanted.
We went from his giving me a little rimming to pinkie finger rimming, trying anal toys (which I actually didn't like until after we had succeeded in achieving proper anal sex) trying different lubes and we are still trying new things, years after we started our learning.
It opened a new door for us, as did learning about toys. I think every new activity or toy you feel brave enough to try can only add to your sexual repertoire. Of course, one should never feel pressured to engage in an activity they don't want to try, or don't like. But, honestly, revisiting one's "hard limits" from time to time only helps one grow as a human being and as a sexual being.
I was vehemently against anal sex when I was in my 20s. I did leave an open mind for "someday, maybe." As I got older, and my husband and I discussed it more, we realized we could learn new things and this was one of them. I'm glad I kept an open mind, even though it took me years of thinking about it. In fact, I wish I had been more open earlier. But, learning this in the last few years has given us a newer technique and activity to keep our sex life fresh.