Start long
Use a longer guard first; you can always go shorter. The back is where most home cuts go wrong.
Bottom up, with the grain checked
Work upwards from the neckline in small passes. Hair grows in different directions on the back of the head, so check the result from more than one angle.
Blend in steps
Use the guard number between your two lengths and flick the clipper outward as you reach the blend line.
Check the back properly
Two mirrors work. Filming the back of your head and watching it on a bigger screen is easier, and is exactly what Shave View is planned to do live.
General grooming tips, not medical advice. If you have a skin condition, a mole that changes, or irritation that doesn’t settle, see a doctor or pharmacist.