Step 2: Braid the hair to be cut
Like a usual hair cut, you should comb and part your hair the way you like it.
Hair can be wet or dry.
Part your hair as usual and comb it. Then, working from the top of the part down, braid small sections and tie them off.
Notice that these braids do not have any french braiding.
Feel out a small patch of scalp, pull together that hair, and braid only that hair. Don't let any strands from other parts of your head get into that braid.
Here are some tips for strategically braiding for this cut.
In the video and pictures I didn't use a mirror while braiding, I just pulled the hair ties so that they were at similar lengths of hair. These braids have a fairly random thickness and weren't "engineered" to generate any kind of undercut or hair style besides what always comes out when I braid then cut my hair.
PRO TIP: The braiding causes a textured look similar to that of professionally razor cut hair. If you employ smaller braids, the result will have more subtle "choppiness." Larger braids will have slightly greater length differences after cutting. The advantage is a dramatic texture, and less work making tons of tiny braids.
Areas where you desire more texture, use bigger braids. If you want the lengths to be less choppy in another area, use smaller braids there.
Tie off areas strategically, the end tie is a marker for where to cut your hair.
If you are using rubber bands, rubber band the braid just below where you are going to cut it. Hair ties are easier to down the braid to adjust.
Obviously hair looks shorter when braided, so don't think about how long you want it, instead think about how much you want to cut off and you will place your hair ties in the right place.
Without a mirror, you can feel where the ties are and know whether they are tied off at the right length on the front and back of your head.
PRO TIP: You can tie off hair at different levels to create a certain effect, such as a cascade of lengths or just shorter hair in the back. If you want to do an undercut, it is best to do two sessions, so you won't get the longer cut braids and the shorter undercut ones confused.