Use your cutting comb to make a part ½ inch to 1 inch back from the hairline. The part should run horizontally across the very front area of your hair, sectioning off the small portion of hair that hangs from the outer tip of one eyebrow to the outer tip of the other eyebrow. Use hair clips to hold the rest of the hair back and out of the way.
Comb all the hair in your new bang section forward onto the forehead. Mist the hair lightly with water. You want them just a bit damp, not soaking wet.
Grasp the middle 2 inches of your bang section between the middle and forefinger of your non-dominant hand. Don't have any tension on this section. You're just holding it in place, not pulling down on it.
Snip the hair so the new length sits at least ¼ inch below the eyebrows (longer if your hair has any natural wave to it). Release the hair, shake that section a bit with your fingers to encourage it to sit naturally, and note the length. If it looks close to where you want your bang length, then use this section as a guide to trim the rest of the bang area. If it looks a bit long, trim another ¼ inch off at a time until you get the length you want.
Once you've got the length of your bangs right, use a straight razor with a blade guard attached to gently and carefully texturize and wisp the bangs. Grab a 2-inch section in the middle (like you did for the trimming stage) and, with your other hand, hold the razor's blade at a 45-degree downward angle in front of your bang section.
Very lightly run the blade down the last inch or two of your bangs in one fluid movement. You don't want to push the blade, or you'll end up taking the whole bang with you. Instead, just lightly caress the bangs so only a little of the hair is cut. Repeat this across the entire bang area. When you're finished, your bangs should have a wispy, uneven texture to them. Good job!
If you want to sweep your wispy bangs to one side, leave the side being swept across your forehead just a little bit longer than the other side.
Always have a blade guard in place when working with a straight razor. These things are beyond sharp, and one slip could seriously injure you.