How to Cut Side Swept Bangs
To cut side swept bangs with shears, hold your bangs on the opposite side of where you want them to fall and separate them into 1 inch sections. Next, position the shears perpendicular to your bangs with the tip pointing down at an angle and cut 1 section at a time as you move diagonally downward. Be sure to keep each section lined up with the others at the same angle and use a mirror to check for evenness as you go!
Make sure your hair is completely dry. Wet hair dries shorter and to a different shape. You won't get the accuracy you'll need for great bangs by cutting them wet. Air drying is best to keep your hair healthy. However, if you're pressed for time a blow-dry is fine. If you have naturally wavy or curly hair, you may opt to cut your bangs while wet to ensure an even cut. If you'd rather do a dry cut, blow them dry and straighten them before cutting. Comb out your bangs. Use a comb to bring your bangs forward over your face. If you don't currently have bangs, create a triangular part. First, comb out all of your hair and part it down the center. Find where your head starts to slope forward. Visualize a triangle made up of this point and the top two points of your forehead, using the arch of your eyebrows to show how wide the triangle should be. Comb the hair in this section forward to make up your bangs. Pull back the rest of your hair. Comb the rest of your hair backwards and keep it in place. Use a hair tie, clips, or bobby pins. This will prevent your hair from falling forward where you may mistakenly cut it. Choose the right scissors. Use special styling shears if you can, as they're sharper and designed for cutting hair, so they'll give you the best results. If you don't have any on hand, use a sharp, accurate pair of regular scissors. Dull scissors will damage your hair by producing jagged ends. Test them on a piece of string to make sure sharpness is adequate. Hold your bangs to the opposite side where you want them to fall. If you want your bangs to fall to the left, you should hold and cut them on the right, and vice versa. Gauge your target length more accurately by holding the bangs in front of the face. Imagine your cut beginning at the tip of the nose and falling to eye level, reaching the cheekbone. Cut your bangs in sections. Start by separating a roughly one-inch wide section of the hair closest to your nose and hold it flat. You will create a diagonal edge where this section will be where your hair is at its shortest. Once you finish one section, move on to the one next to it. Keep each section lined up with the others at the same angle. Use a mirror to check for accuracy and evenness. While cutting, position your shears perpendicular to your hair and then point the tip of the shears down at an angle. Working with smaller segments will take longer but produce better results. If you're trying a new look, cut your hair a little longer than you want it. You can always go back and trim it shorter if it ends up being too long, but it will take a few weeks to grow out if you trim it too short. Re-comb and reevaluate your new bangs. Return your bangs to the position you want to keep it. Make sure your bangs are how you want them. Check how the angle and length look on your face. Look for any uneven sections. Touch up any errors. If you've missed any sections, trim those to match neighboring hairs. If any sections are uneven, redo those to create a neat diagonal line. Cut vertically instead of at an angle for this step for better accuracy. Style your bangs. Once you're happy with your bangs evenness, style them for one last quality check. Use a round brush and a hair dryer to sweep your bangs to the side you want them to be. A small amount of mousse will add extra volume to your new look. If you have thicker hair, you can follow-up with a flat iron or curling iron to style your bangs. Choose an appropriate razor. This can be a straight razor, a hair shaper, or even a disposable shaver. Just ensure that your razor is very sharp and has a single blade. Using dull tools or ones with multiple blades can cause split ends. Professional hair shaping razors come with ergonomic handles especially designed for cutting hair. Using a razor for extremely coarse or curly hair might not be your best bet, as this sometimes also causes split ends. Take hair one segment at a time. Start with the section closest to your nose. Just as you would with scissors, hold one section of hair at a time while cutting for the best look. Remember to keep your sections to about an inch long or shorter to prevent over cutting. Pull each bang section taut. Use your middle and index finger to pull your hair up to form a 90 degree angle with your face. Slide your fingers down towards the tips of your hair. Hold them just above where you plan to cut. Run the razor across your hair. Use your razor to gently cut into the hair section by section to form a diagonal. Use a gentle gliding motion away from your face. Keep each section lined up at the same angle. Continue until you reach the longest part. Check your bangs when finished. Comb out your bangs and position them towards the side where you want them to fall. Check for sections you've missed or uneven breaks in the diagonal. Correct your mistake by pulling the section forward again and trimming it back with another stroke of your razor. 
Make sure your hair is completely dry. Comb out your bangs. Pull back the rest of your hair. Choose the right scissors. Hold your bangs to the opposite side where you want them to fall. Cut your bangs in sections. Re-comb and reevaluate your new bangs. Touch up any errors. Style your bangs. Choose an appropriate razor. Take hair one segment at a time. Pull each bang section taut. Run the razor across your hair. Check your bangs when finished. 