I'm not a great one for signing up to classes; I prefer to learn things from a book, privately, and work at my own pace. Richard Hittleman's 28 Day Yoga program is perfect for that. It leads you gently, step by step, through 38 basic yoga positions over a month, building steadily and carefully to ever-greater challenges, and leaves you with three basic daily routines to practise at the end. I followed those daily routines for many years -- not always daily, but regularly. But it's been great to go back to the start and ease into it again. Having not done yoga at all for a long time, I can really feel the difference in my body -- I feel looser, lighter, fitter and more supple.
A word of warning: the book was first published in the 1970s, and it shows. Each day's program (taking about 20 minutes to complete) ends with a 'Thought for the Day' on topics like nutrition, smoking, the benefits of gentle stretching etc. There is much wisdom here, but also much dated hilarity. The reader is assumed to be a 'housewife.'
If the activities of housework (cleaning, shopping, child care) constituted true exercise we would not see the housewife tense, irritable, overweight, flabby, depressed and complaining of many aches and pains.There is also an unhealthy emphasis on how yoga will make you beautiful! So take all that with a pinch of salt. But the exercises themselves are fantastic, and the program is so carefully structured, it's a wonderful introduction to yoga.