Copied from my thread on Den of Angels:
You could cut your wig a little shorter than how mine is, but perhaps not exactly buzz cut short since the color of the base of the wig may be a different color than the hair, making the hair look too thin.
So here's what we're starting with:
You can see that it isn't a perfect fit right off the bat. The sides stick out significantly so you can see a big gap between the temples and the wig, and it tents at the top of the head, a big empty gap there inside:
Step 1: Fix the Fit
You can pinch or pin the wig at the temples and the top of the wig to determine how much you are going to need to cinch it from the inside, then turn the wig inside out and note where you will need to sew to make it tighter. Here is a picture of the inside of the wig with the sewing adjustments made:
Optional Step 2: Tuck the front of the hairline if the bangs aren't combed forward
If you are going to comb the hair forward so that the hairline doesn't show, you don't have to worry about this. If you want the front of the hair to stick up, in order to avoid seeing the rough edge of the wig, you fold the front under and sew it down. I hope that's clear... I can't think of a better way to explain it and hopefully the image will help. You'll have to use a pin or needle to pull out some hairs afterwards that will likely accidentally get sewn down as well.
Step 3: Cut the wig
Ideally with an electric razor that has some length extensions on it so that you make sure you get all the hair the same length and it's faster that way as well. I used a shorter extention for cutting the sides and back. At this point, you will notice the hair will be choppy because it is all the same length. The next steps on texturizing will help to get attain a more natural look.
Step 4: Texturizing
I don't have pics of this step from when I worked on the short wig, so I'll be using pics from another wig for this part. Here is the wig before. You can see the choppiness:
The texturizing process:
This is very time consuming but well worth it. You have to go over the whole wig, take small portions of hair and cut them at a steep slant like so:
As a result, you can see a much smoother and softer look compared to the before image:
The original wig complete: