Some hints on doing Ashtanga Vinyasa Hatha Yoga Safely
In addition to the tips on practicing Hatha Yoga, here is some specific info. based on my experience with practicing Ashtanga Vinyasa Yoga:
Note that I am NOT a teacher of Hatha Yoga and I certainly am not able to turn myself into a Pretzel!!
In general I have three layers on - close fitting stretchy stuff, following by a sweat shirt, followed by light nylon windcheater top and bottom. This combination ensures that in the European winters, my body not only gets hot quickly but retains the heat as well.
I never push too hard with Ashtanga Yoga - the heat does 80% of the purification and the increase in flexibility
For absolute Hatha Yoga beginners, I strongly recommend practicing normal (Iyengar or Sivananda...) Hatha Yoga once to twice a week for one year before trying out Ashtanga. The reason is very simple, in Hatha yoga one needs to concentrate on breath, posture and balance. This takes time. In Ashtanga yoga, the postures are held for less time, the movements are faster and because of the heat it is easy to push yourself too far without realizing any damage until its too late. To manage this you are better off with some prior experience.
The Primary Sequence is designed very carefully, I know from experience that to skip postures and go on is definitely not a good idea. Each asana is a preparation for a following asana and so strict order is essential (subject to specific changes that are given to students by authorized teachers). This does mean that in the beginning students may not be doing many asanas in which case you can make more of a workout by doing more Surya Namaskars A and B, for instance when I first started Ashtanga I would do 20 Surya Namaskars A and 20 of B.
There is a tendency in some students to rush through the sequence. In the long run this can cause problems. The Primary Series is about developing strength as well as elasticity. The strength is necessary to protect joints from over-extending. This strength can only be developed if the student takes time to allow the isometric strength building aspects of the yoga to work through the body. After many years of practice and resulting problems, I am now convinced that any hatha yoga practice must be supported by a series of isometric exercises.