Ok, this is a technique to make a simple temporary cloak. It is not the same as a shield. It is meant to be used in situations like having to mix with the public for a short time. I do so dislike the energy of less desirables mixing with mine. It is also effective if you are with a leechy type person, - they actually get somewhat bewildered by it. I usually put on a cloak when I have to go shopping, or socialising, or such.
It starts with a grounding exercise. Stand up with your feet about a foot apart. If you are not too good at centering, you can still do a grounding exercise, by standing up, being still, lifting your toes up (so you can feel the soles of your feet on the ground better), and visualising roots growing downwards from the center of your feet into the molten center of the earth. Simultaneously flow the energy down, and draw it up.
Now put your arms in the air, palms up. Have a good stretch. In one movement, bend over and sweep the energy from the ground, up over the front of your body, (touching), over and above your head, and make a big circle from over your head, and around the sides of your body, like wings. Let it run down your back to the ground.
Let your arms hang heavily, and feel the chi dripping into the ground. Try to visualise, during the process, that a fabric cloak is being made. I usually choose blue, but it's up to you. Think about what you are doing!
Repeat the motion three times. You can do this at the beginning of each day. If you use a colour, it is easier to re-enforce it at an acute time if needed.
And there is your cloak, with a bit of free yoga! :)