How to Cut a Man's Hair
To cut a man's hair, start by trimming the sides and back with clippers while their hair is dry. Use a high-number clipper guard if you want to keep their hair long, or a low-number guard to cut it shorter. Once you've trimmed the sides and back, dampen the hair on the top of their head and comb it out to get rid of any tangles. Then, use scissors to cut the top of their hair. To finish the cut, trim their neck and sideburns with a clipper and no clipper guard.
Ask the man how he wants his hair. In a consultation, find out how short he wants his hair, how uniformly he wants it cut, and how he plans to style his hair afterwards. He may want you to only trim away split ends, but he could also want you to cut everything off. Before you begin to cut, it's important that you ask all of the necessary questions and understand what he would like done with his hair. If you are clear and communicative from the start, you will avoid any potential misunderstandings. When cutting men's hair, break their head up into 7 parts: the top, left side, right side, back, left sideburn area, right sideburn area and the fringe. That way, they can describe to you how much hair they want taken away from each part. Make it a dialogue. As you cut the man's hair, continue to ask him for feedback. Give him access to a mirror (wall-mounted or hand-held) where he can review the cut, and periodically ask him whether it's short enough. Choose a haircut that will suit the man's face and the amount of hair he has on his head. A man who is losing his hair on the top of his head may love the way Don Draper looks, but may be disappointed when he tries to pull off the same look. More dramatic hairstyles on men tend to work best when a man has a fuller head of hair. More conservative hairstyles tend to make the best use of thinning hair. Make sure that you have plenty of time. It is important not to be in a hurry when cutting hair, especially if you do not have a lot of experience. You also do not want to have any sort of stimulant in your system, nothing that will make your hands unsteady or interrupt your concentration. Set up the work area. Seat him in a sturdy chair, and make sure you can comfortably reach his head with your hands. Cover his shoulders with a barber's cape, bed sheet, or towel to keep the hair off of him and to make cleaning up easier. Try fixing the sheet around his neck with a pin or a clip so that it doesn't slip off. Cover his neck with a neck strip, which you can buy at a local beauty supply store. Make sure to set up on a floor surface that will be easy to clean afterwards. Tile, wood, linoleum, and concrete are all great choices. Carpet—especially thick carpet—will swallow clipped hair and make cleaning up difficult. Bathrooms, kitchens, and patios are good for hair-cutting. Use a pair of very sharp, high quality shears that are specifically made for cutting hair. Scissors made for cutting paper or fabric will not lead to the results you want to achieve with his hair. Always start with clean hair: if you are using electric clippers, start with dry hair; if you are using only scissors, slightly damp hair is easier to work with. Dampen his hair by spritzing with a spray bottle. If the hair is too wet to work with, towel it gently dry. Detangle his hair by running a comb through it. This should also give you an idea about how and where to cut. Comb hair in the desired style: some men prefer the part on the right side of the head, and other men prefer it down the middle of the head. Choose a clipper attachment. You can use the clippers to trim the back and sides of the head, to tidy up loose bits around the ears, or even to buzz the entire head to a uniform length. Clippers come with blade-guard attachments that determine the length of the hair that gets cut. The longer the attachment, the less hair that gets cut. Many men have a preference on what guard you use, so it's a good idea to ask him if there's one that he prefers. Most clipper sets come with six guides. The lower the guide number, the shorter his hair will be: Use a six to keep a little length. Use a three or four for a classic cut. Use a two for a close cut, and a one for a "buzz cut". Hold the clippers firmly between your thumb and first two fingers. Your grip should be strong and steady, but comfortable. You don't need to squeeze or do anything fancy with this clippers; you might hurt someone. Start clipping at the base of his head. Hold the clippers against his scalp, and run them through his hair from the nape of his neck to about halfway up his head. Round the clippers up and out to finish that cut. Work around to the sides, always cutting upward and against the direction the hair is growing. Work your way slowly around the head. Cut carefully around the ears. Leave the top for the scissors. Line up the back of the head. To line up the back, the goal is to keep the existing hair line, and take off the strays outside of the hairline. Turn the clippers upside-down and press the blades perpendicular to the head and cut downwards. Be sure to get the rat-tail in the middle. Whoever does the line should have the recipient look down to get a close cut, then look up to preview what it looks like when finished. Line up the sides. The sides are trickier than the back, but the goal is usually to push the line up and off the ears. Turn the clippers on their side and use the edge of the blade, cutting from the back to the front, going against the grain. Try to tilt the blades at an angle so it fades in. Dampen the top of the man's head, and comb the hair forward. Use a spray bottle to lightly spritz the uncut hair. Comb the hair forward and make an imaginary line down the center of his head, as if it were in between his eyes separating the right side from the left side. You can also section the hair with clips if you need to. Trim the top. Beginning at the back and working forward along your imaginary line, comb up a half-inch section of hair. Pinch the hair between your index and middle finger, slide your fingers up or down to the length you want. The hair below your fingers will stay on his head; the hair above your fingers will be trimmed away. Snip the hair at an angle, with hair-cutting scissors, so it won't look blunt or uneven. Cut perpendicular to the hair direction for a clean cut. For example, if his hair points downwards, towards the back of the neck (vertical), cut horizontally across the back of his head. Don't cut in one big clip with the whole scissor blade. Use the tips or the scissor blades for cutting in short spurts. If you're nervous, cut just a bit at a time. You can always cut more if you need to. After cutting your entire line, comb the hair forward again and begin at the very front of the head. You should notice the length difference where you just cut. When cutting a new section of hair, always take part of the just-cut section between your fingers so you can use it as a length guide. Blend the top of the head. Cut along another imaginary line. Using the prior cut as your guide, make another "line" to either the right or left of your original one. Begin cutting, once again, from the back of the head to the front. Use the already trimmed section as a guide and cut any hairs that stick up past that length. Continue sectioning and cutting the hair from front to back, always taking a bit of the previous section to show you where to cut. Trim his bangs. When you reach the front of his head, comb his bangs down. Ask him how long he wants his bangs to be if you didn't already during the consultation. Holding the scissors vertically with the tips pointing up, make little snips using the points of the scissors. Cut at an angle for better blending. Be careful with bangs. The "golden rule" is: "Once you cut it, it's gone." Always remember that you can cut more off, but you can't add it back, so you must be sure of where you're cutting. Make sure that the bangs are damp, but take drying into account. Cutting dry hair causes it to fly everywhere, and can fray the ends in some cases. However, curly hair can shrink up to 4 inches (10.2 cm) when it dries. Even straight hair can shrink as much as 1 ⁄ 2 inches (3.8 cm). If you haven't cut bangs before, err on the side of caution. Blend scissor cuts with a clipper cut. Using the fine-tooth end of the comb, comb upward at the point where the clipper cut meets the scissor cut. Use the scissors to trim the hair that pokes out of the comb, blending away, or 'fading,' the harsh line that separates the clipper cut from the scissor cut. This is called the shear-over-comb technique. Work all the way around the head. As you use the comb, hold it with the teeth pointing straight up, making sure you aren't angling it towards or away from you. Trim his neck and sideburns. Using the clippers without an attachment, trim the neck and hair around his ears. Trim his sideburns, stepping back occasionally to look at him head-on and make sure they're even. Start at the top and work the clippers downward so you don't clip too high. If he asks you to trim his beard, you can use the clippers to either shave or clean up the hair below his sideburns. If you are shaving, you can use a razor (for a close shave) or the clippers without any attachment (for a rough shave). If you are cleaning up the beard: ask him how short he'd like it, and choose a clipper attachment accordingly. You can also use scissors to evenly snip away the longest hairs of his beard. Comb one last time after the entire head has been trimmed. Look over to make sure that you haven't missed any spots. Carefully touch up any rough areas with scissors or clippers. Let the man see your handiwork in the mirror, and ask for feedback to see whether he likes it. You can always cut more if needed. Make any final touches to the cut. Wash or spritz his hair one more time, just to clean out any lingering hair clippings. Gently towel his hair and neck dry. Consider briefly blow-drying his neck to remove any loose hairs. Add styling products, if the man wants you to. Sweep the floor before you let him out of the chair. Take a minute to sweep all of the loose hair clippings into a small, out-of-the way pile. This is a necessary safety precaution to take because hair can make the floor very slippery. Afterwards, wash your comb/scissors/shaver. If he isn't wearing shoes, the hair can go through his socks. Sometimes you can get an ingrown hair, where a hair grows the wrong way. This is very painful. If he is wearing shoes, the hair can stick to the soles of the shoes, and could be dragged around the house. 
Ask the man how he wants his hair. Choose a haircut that will suit the man's face and the amount of hair he has on his head. Make sure that you have plenty of time. Set up the work area. Always start with clean hair: Detangle his hair by running a comb through it. Choose a clipper attachment. Hold the clippers firmly between your thumb and first two fingers. Start clipping at the base of his head. Line up the back of the head. Line up the sides. Dampen the top of the man's head, and comb the hair forward. Trim the top. After cutting your entire line, comb the hair forward again and begin at the very front of the head. Blend the top of the head. Trim his bangs. Blend scissor cuts with a clipper cut. Trim his neck and sideburns. Comb one last time after the entire head has been trimmed. Wash or spritz his hair one more time, just to clean out any lingering hair clippings. Sweep the floor before you let him out of the chair. 