If you have long hair, getting it cut can be extremely emotional. Crying is not uncommon, because it took years and years to grow your hair. It's been a part of your self-image for a long time. Then suddenly it's gone! It can be devastating, even if you wanted the haircut.
If you don't want to pay extra for a shampoo, some salons will spritz your hair with water to dampen it. The last time I had a haircut, I had waist-length hair, so she took me to the sink, but only wet my hair down instead of using shampoo. My hair was simply too long and thick for a spray bottle to work.
After that, they'll take you back to the chair and wrap a cape around you, to prevent hair from getting on your clothing. Glasses must be removed. If your hair is long, they'll put it in a ponytail first and cut that off. You can keep it, if you want, or you can donate it to a company that makes wigs for cancer patients. However, when I researched these companies, they apparently don't give the wigs to patients, but sell them. I thought that smelled of a scam, so I decided to keep my hair.
They will ask what kind of haircut you want, and if you provide photos, the stylist will bless you. It's hard to work off a verbal description! I always print a photo of the hairstyle I want, front and back. To get started, they will divide your hair into sections, clipping them (with jaw clips) out of the way while they work on one area at a time. There is a lot of combing involved while they work. They really get in there, using their fingers to move your hair around, checking to be sure each side is the same length, and so forth. Sometimes they'll use a special tool to add texture or thin your hair out. This can be quite painful, since they yank on your hair as they're doing it. If your haircut is extremely short, they will use an electric razor to shave the back of your neck. I hate this, since it always grows back before I can return to the salon, so what's the point?
Once they're done, they'll usually apply some kind of product to your hair and style it as they blow it dry. I usually don't agree with the stylist's idea of "pretty" . . . it often involves lots of teasing and poofiness, which I abhor.
If someone has curly hair, cutting it requires special training--which most salon workers don't have. For instance, you don't want to cut it wet, since that straightens it. Once it dries, the curls tighten and your haircut is suddenly several inches shorter than you thought it was going to be. They also tend to use a straightening iron or blow dry your hair straight, which is annoying (to me, at least) because I don't have time to do that at home. I want my haircut to represent what I will see when I wash and dry my hair myself, so I'm not disappointed when I get home. I've only had one stylist who actually realized my hair was curly. I didn't know it myself at the time, since I'd always brushed my hair out, so it was extremely frizzy, but she showed me how to apply gel and scrunch my hair, instead of brushing it, to bring out the curls. It was amazing! For the first time in my life, I had pretty hair, instead of a frizzy halo.
I don't know much about perms, except they aren't that popular these days, unless you're a little old lady. Perhaps spiral perms are more popular? The chemicals are harsh, so they probably wouldn't redo a perm unless it had been several months. And like others have said, you can't really ruin a perm by getting it wet, unless it's right after it was done. And in that case, it would be dangerous to redo it. The chemicals might disintegrate her hair or cause it to become brittle and break off.