You need the easiest warm-up exercises in order to boost your blood circulation and loosen your muscles ! Many times, we jump to full-scale session and in this way give an unpleasant ‘jerk’ to our physical system. The following easy-to-do limbering practices will help you get ready.
i) Lie straight on your back on a flat, even surface or yoga mat which should be not too hard not too soft/bumpy.
ii) Fold your left leg and draw your knee near to chest, can hold the knee to chest for a few seconds or up to for 10-15 seconds.

iii) Do this for the right leg
iv) Repeat this once again at least. Can be extended up to four rounds.
v) You can practice leg raising with each leg alternately for several rounds and extend up to both legs at a time
vi) You can move your legs in a bicycle pedaling manner while still laying upward straight on your back.
vii) You can now turn round to your front and raise your bend ankles after folding your knees.

viii) Now yo can raise your chest taking support of your hands on both sides while/with inhaling.
ix) Your can also follow free hand exercises for warming up to your main session. But keep in mind to lie down to take rest then before beginning the main session consisting of enhanced bends and arches.
x) Before you go for any full-scale bendings and stretches, do these in milder forms, to be more alert and careful and to avoid possible hurts to yourself.
xi) Pawanmuktasan poses can also act as a part of a warm-up session. But, in such case, Pawanmuktasana poses should be used, not as yoga poses, but as freehand warmup exercise!