As there will likely be some folk surfing across this post who do not have a yoga practice but have considered starting one, what better topic than how to get going beyond the cursory instructions of "go".
First, a basic definition of right yoga. By "right" I mean appropriate for the practitioner. I do not mean yours is right and hers is wrong. The bigger question now is "how do I determine what is appropriate for me?".
As we move through this, try to keep the concept of intention in the forefront of your mind. Everything flows from your intention.
There are two pragmatic ways to add yoga to your life. (This presumes you are not just throwing it in there, which may be perfectly fine for some.) One I will call more of the same and the other I will call countering your life.
More of the same means if you are a running, scheduling, pressed for time, competitive, fiery sort you can have more of the same and add a yoga practice that fits within all of this. Likewise if you are more akin to a slow walk, a quiet read, less action, less doing, you can find a yoga practice that fits this grouping as well. Either way it is more of the same. More of the same can be fun, entertaining, unifying, but it is rarely balancing because it's very nature is, well, more of the same.
Countering your life is embracing a yoga practice that is not the same as the rest of your life. If you are fiery you opt for a gentle practice. If you are sedentary you opt for a bit of activity. If your nervous system is in crisis you calm it. If it is repressed you give it a boost.
There is one caveat and that is this, a well crafted practice may, and I stress MAY, have both offerings contained within it. This is less likely with extremes at either end of the fiery-sedate continuum.
The punch line. How do you know. How do you find the good practice for you?
Over time it is fairly easy to make such a determination. The practice should have an effect on the student's life off the mat. If you've been practicing for several years and you're still the angry freeway driver you once were, then it's possible you've chosen a practice that is not effective for you. If you do not manage the relationships of your life one iota better than you did several years ago before yoga then you may have selected a practice that is not effective for you. It is merely self-deception to believe that we can keep doing the same things and have different results.
In the short term I suggest the following:
Set aside a few quiet minutes for yourself after class. Make this undisturbed time, uninterrupted time - no calls, no chat, no assault on your nervous system. Then gently go inside yourself and mine the residue of your practice. Find what has been left over, what the practice has done for you. And while you're doing this keep the sense of achievement and doing and power off to the side. From this process you can determine what practice is the right practice for you. Then do it with unbridled joy.
Gordon you bring up such a great topic with the idea of finding balance in your practice. Often those very people who are typically on the go, run hot, and are likely full of stress, tend to find yoga classes that offer them hot, fast and challenging practices. And vice versa. What a good way to introduce some ideas about conditions and tendencies and dare I say it? Doshas. I love when a teacher can make a seemingly foreign thing seem very much understandable and applicable. Of course it's not in the extreme, it doesn't mean you always have to do a restorative sequence if you're a go-go-go kind of person, again, it's about finding balance and tuning into your bodies needs at any particular time.
I often say to students who ask me about finding the right "style" of yoga, or the right teacher, or how often they should go, not to be dissuaded by the first class they try out. Often it takes much experimenting with all kinds of different classes and teachers to find out what we like and more importantly, respond to best. This is especially true for students who are brand new to yoga and are likely to be put off by their first bad or unthrilling experience.
You bring up good points, but I think that people are drawn to the type of yoga that is precisely perfect for them at that time.
I have a young friend - he is 10 years younger than I am - who works as a lawyer. He runs around all the time seeing various friends and is spiritual but not to the point yet where he would go deep into it or wear it on his sleeve. I took him to Sivandanda Yoga - he hated it, called it "Hippie Yoga" (jokingly). He took me to YogaHop - about the sweatiest, loudest, hip-hop music blaring yoga class you could ever find.
I enjoyed the YogaHop but I prefer the "Hippie Yoga." But in my 20s I would have never gone for the spiritual yoga. It would have totally turned me off. I started Kundalini Yoga last year but if I had gone a year previous I would have hated it. So I think you go where you need to be.