So in the practice of mahamudra, you first sit in vajrasana

So in the practice of mahamudra, you first sit in vajrasana. Then stretch one of the legs forward, keeping the knees together and place your hands on the knees. Do jalandhara bandha, concentrate three times on mooladhara chakra. Then draw the breath in with ujjayi through the frontal passage right up to bindu, and hold the breath there for three seconds.

Hold your toes, do shambhavi mudra, focusing your eyes on the eyebrow centre. Also do khechari mudra by folding your tongue up against the palate, and moola bandha, contraction of the anus. Rotate your awareness alternately through these three centres - shambhavi, khechari, mool; the eyebrow centre, the place where the tongue touches the palate, and the completely contracted anus - a maximum of twelve times. Then bring your hands back to the knees and draw the breath back down to mooladhara. This is mahamudra. Do it four times, and then see how your mind is.

One should learn all seventeen kriyas from the guru or his respective teacher. If you have time enough to practise all seventeen, then do so, but if you are short of time, then you should consider maha mudra, maha bheda mudra and naumukhi to be the most important. After practising these three, if you find that you still have time, you can practise vipareeta karani mudra, and if you have more time still, you can practise shakti chalini.