You may continue to lie down if you wish, or stand. I have always found it most effective to have my body in an open position, not sitting cross legged or with arms folded, but spread out so that more of the skin has access to more of the air around me. Working skyclad can be helpful, but is not necessary. Reach out with your hands and feel around you for the element you are going to be breathing in. Feel for the air, water, earth or fire in the space around you. If you're lying down, connecting with earth is easily done by putting your hands on the solid surface underneath you. Imagine that your skin on your hands is a breathing apparatus, and start drawing in the energy. Once you have that feeling, open up all of the pores on your flesh are opening up and breathing in that energy. Your whole body is a magnet, pulling in that elemental energy and imbuing your pattern with it. Pull in as much or as little as you need.
If you're pore breathing, it's important to remove from yourself what you don't need so you are not in a state of unwanted unbalance. You can simply return it to the earth by placing your hands on the ground or hugging a tree. You can also use it to charge an object; you can add it to your elemental tools, charge a charm with it, or store it in a stone for later use. You can charge something around the house with it. Put the extra earth energy in your wallet or the fire energy into your running shoes. Of course, make sure to keep what you do need, but no more.
Pore breathing can be done for a number of reasons. The most obvious is to correct an elemental imbalance. Feeling anxious and wound up? That's a symptom of an overabundance of fire, so breathing in a little bit of the grounding, solidifying energies of earth can help bring you to a more balanced state. Feeling sad and blue? A little of the uplifting air energy can brighten your day.
Taking a few moments to breathe in elemental energies can be useful in a number of situations. Going to go flirt with that gorgeous person over there across the room? Be red hot - breathe in a little fire before you do. Have a tough exam you need to pass? Breathe in some air energy to clarify your mind before starting. Once you have a familiarity with the techniques of pore breathing, you can do it anytime, anywhere.
For such a simple technique, it's a very powerful way to invoke the powers of the elements into your magical workings, and into your daily life. The skill's flexibility and broadness of use make it a very valuable addition to my magical toolbox.