The Laws of Prayer /The Blessings of the Shema (62)

1. When saying the word “Echad” in the first verse of the Shema, he should concentrate on the fact that Hashem reigns in the heaven and earth, is unique in the universe and reigns in the four directions of the earth. Some say that all of this should be while saying the final letter (“Daled”), whereas others say that while saying the letter “Ches” one must concentrate that Hashem rules over the heavens and the earth, and during the letter “Daled” he should concentrate that Hashem is unique in his world and reigns over the four directions of the earth. (Shulchan Aruch and Mishne Berurah 61)

2. Some have the custom to move the head according to the idea about which one is concentrating, up, down and to the four directions, in order to arouse the concentration. When moving towards the four directions one should do it east, north, south and west in that order, and not east, west, north and south as that looks like a cross. (Shulchan Aruch and Mishne Berurah ibid)