I watch a student the other day, she was cutting a one length haircut, a simple haircut that I have seen this particular student complete and do it very well. This time however she seemed to just not get it right, whether this was down to a large amount of lack of concentration, I think this would have contributed a large amount, but what was interesting was was two areas that came to light, these were the students positioning and perception.
Positioning of a client, there head and yourself will play a part in getting a good haircut. You may have heard about clients who cross there legs and sit at a slant, there shoulders being at different heights, to correct this simply ask your client to uncross their legs. Head positioning is something crucial to a good haircut as you can eliminate unwanted graduation through the back of the haircut, if the head is placed forward you will end up with a crisp line in the cut.
The other part of the positioning is the position or posture of yourself as a hairdresser. If you stand crooked there is a good chance the haircut you do will be crooked. if you stand squarely in the center of a client, at the back of a one length haircut and plant your feet, do not move them, and work in the center and to each of the sides of your one length haircut, your posture will be correct to make a straight haircut.
I see students who have not yet built the stamina to work through a full day haircutting, they lack the concentration and physical presents to stand correctly, they invariably stand with their weight on one foot making their hips slant, and this effects the plain that there arms can move on, it is this lack of posture that make you complete a poor haircut.
Another area is perception, try thinking that if you hold a broom handle, level across the line you want to cut on a one length haircut, this may help you with the over all perception of your haircut, it may help you visualize the line on which you will be cutting.
Enjoy your hairdressing.