To get a DIY number 4 haircut, first, you need to arm yourself with trusty clippers and a bunch of different clipper guards. Now, follow these steps:
1. Attach the guard #4 to your clippers and trim all the hair on the sides, starting at the hairline and moving toward the crown.
2. Switch to the guard #3 and trim the sides once again but this time, indent 1 in. from the crown.
3. Repeat step 2, indenting an inch from the previous indention.
4. Outline the edges with a razor or trimmer for a clean look.