Rotation methods vary. Some people go in a clockwise rotation, with every injection 1 inch away from the injection site before. Some people go side to side in an area, keeping a 1 inch distance between injections, until all available sites have been used in that area.
Rotate sites within a particular area, such as the left side of the abdomen or the left front of the thigh, injecting 1 inch from the previous spot each time. For example, start with the left thigh until all injection spots in that area have been used. Then, switch to the right thigh. By the time you get back to the left thigh again, the tissue should be healed and ready to accept insulin again.
The same method can apply to the abdomen. Start on the left side. Move over 1 inch, in a clockwise or side to side progression, for every subsequent injection until all areas of that side have been used. Try not to randomly inject, but to keep track in an orderly way so that all available areas are eventually used and no area is used twice. When all available sites have been used on the left side, switch to the right and proceed the same way. Never inject within 2 inches of the belly button.