True that:
I tried to steer away from such oddities as slaps, slap-pounds, odd handshakes and other small group insider-greetings, as well as nods, bows, winks, waves, shoulder-grabs, arm slaps and other less common greetings.
And I didn’t even get started on how Brazilians will VERBALIZE a greeting.
In England, we have a variety of ways to greet each other. Some people, mostly men, will simply greet with a handshake, and saying “good to meet you.” Women sometimes do cheek kisses, though this is mostly a formal thing.
Male greeting depends on a lot of things in Britain. Those things are as follows:
When greeting someone after meeting them for the first time, it is generally customary to shake hands, or just wave hello, and give the verbal greeting of choice, which is quite often either “How nice to meet you!” or “Good to see you again!”
If meeting someone you are more friendly with, handshakes or brief hugs are not uncommon, although they are not as common as other greetings, mostly due to some groups still seeing men hugging as being “a bit gay”. Plus, British people tend to prefer personal space more than some other cultures.
When meeting someone of high class, such as perhaps the Queen, who likes to pop round every now and then for a cup of tea and a chat about the weather, we tend to bow.
When greeting someone you are close-ish friends with, hugs are slightly more common than before, mostly due to being more comfortable with them as a person.
When greeting a very close friend (of a young, working class background), it is customary to have a casual exchange of insults, followed by invading their space as much as you can, and implying that you have recently achieved sexual congress with their mother. The “bro-fist” will also suffice.
Time to add how greetings are made here 
When people meet for the first time or it is a teacher or a bigger person then you are expected to do the handshake as a formal greeting.
For relatives the most common way to greet each other are either hanshake or brief hugs.
Among friends just saying hi or if you know them well you can either do the “bro-hug” or hug, handshake works too, there is no rule here how to do it, just see how the other person wants to greet is a good idea 
In university just saying hello or uphead-nodding is made, barely any contact is made among persons here, except if you have known the person for a very long time
If it is someone you havent seen for a long that you know Quite well then hugging is expected
Also this pass by greeting Mag said is common in every village that is not in town-class
I hug friends and shake hands with strange. Applies to both sexes.
Oh yeah, informal greetings, with close friends can be pretty much anything. Specially with weird firends 
. I have an old school friend I always do this complex sequence of handshakes with. We started doing it in third grade and now it’s just weird when we don’t… 
I’m not sure insults are reserved to just very close friends or the young. Although it does kinda indicate a trust between you, that you won’t take offence. Things like “How are you doing you old #insult#?” The severity of the insult would indicate how close you were, the stronger the closer. Although with the older generation or with those who don’t typically swear, using harder swears would probably cause some discomfort or offence. Variants involving sexual congress with their mother would probably be exclusive to the younger generation. It probably also does appear more in a working class environment.
Cheek kissing is something that tends to be between relatives or close female friends towards males from what I’ve seen. Especially female older relatives like grandmothers or aunts towards grandchildren etc. I did once have somebody I vaguely knew cheek-kiss greet, I wasn’t happy about it to be honest and felt it a violation of my space. (I also didn’t trust them because of past events, which probably didn’t help things.) The number of kisses would probably vary, but might be 1-2 kisses alternating cheeks if more than 1. It might or might not also be exaggerated with “mwooooh” sound effects.
It’s perhaps not quite the same thing, but I feel awkward when somebody wants to shake hands with me, but I know they are sick. Not seriously sick, I mean things like a cold or such. In such a situation it feels it would be better to say something like, “I would shake hands but I have a cold” or some such. Certainly if sick this is what I would do. It seems fair to me if you are sick to avoid contact if possible. I would be very annoyed if somebody tried to cheek-kiss me when sick like this.
o.O I didn’t really think about how ritualized it is here until you said it’s abnormal.
Here in the… Upper Southern US(I guess? o.O ) A handshake and a "Nice to meet you smile " is pretty much the standard between strangers. If meeting a male authority figure, a firm grip is expected, if I’m meeting someone like… Oh, lets say my dads friend, trying to crush the other ones hand is expected. Male meeting a woman is firm but definitely not a hard squeeze.
Among friends it varies greatly between social groups, I know a lot of people around here sort of nod and say howdy (Not kidding). Most of my friends exchange hugs, shorter “bro hugs” between guys. Between two women or a man and woman it depends on the level of friendship. Of course if you see someone in passing a “Hey!” and a wave or something similar is acceptable.
Actually, a funny story with a friend of mine (Bad language involved, I'll use ** but still):
Walking down the hallway at my old high school and I see a kid I'd gone to school with for 5+ years but never really hung out with or knew very well at all comes down the hall way going the other way. We make eye contact and start to greet each other like you normally would in passing but for some reason, we both kindof looked at each other and exchanged grins and said "F- you Kaleb" and "F- you Devin" at the same moment and continued on our way, laughing as we did. We continued to greet each other this way for the remainder of the school year and in the few times we've seen each other since. The funnest part of the story to me is that prior to this, I probably wouldn't have said he was a friend, or that we had spoken in years. Somehow this was a bonding experience between us. :lol:
I forgot! They did that in Texas, too! And some actually wore cowboy hats and tipped them, seriously! Though, maybe they were just doing it to humor me.
Also, another weird things American’s done. When you walked passed someone, if they knew you they’d say “Hi!Howareyou?!” all really fast while -still- walking passed you. By the time you stammer “I’m okay! Nice to see you” they’re already gone. o.o It’s like no one ever actually stopped, and if they did then only for a second. It was strange to me, because I’m so use to people actually being interested in conversing.
Well, an American would know that the exchange was going to happen this way, and react just as quickly 
Here it’s more of a “Hey!” or a “Hey what’s up!?” spoken pretty much simultaneously. Usually accompanied by a head nod or a quick wave.
Of course, girls from my high school perfected the "DEVVVIIIINNN!!! tacklehug and gone before I figured out who it was x.x
What everybody seems to have in common is that there are many ways to greet depending on the person and the situation. We can agree that handshaking and nodding are pretty universal if you want to show respect for the other person.
Here in Uruguay:
Both men and women / Family and close friends:
One kiss on the cheek and a hug.
Among men, the older they are and the weaker the bond is between them, the kissing part decreases and it turns to handshakes or pads in the shoulder, stuff like that.
Young people, men and women, will usually kiss once on the cheek:
a friend, a close co-worker, friends of a friend (if the friend in common is around - if not, just “hi”)
If you enter a public place, like a store, you only say good morning or good afternoon.
There are many variations depending on your own style and preferences. I try to adapt to the other person, but I don’t like more than one kiss on the cheek. It confuses me . Should I do it? Should I stop? How many kisses? 2 or 3? (this happened to me yesterday and it was awkward)
Oh! And if you enter a room full of people you know, some people will kiss each and everyone of them. That’s too much for some people (like me) so we wave and say a general “hi!” and people are not offended. They understand.
Well in Sweden people tend to be rather reserved in everyday situations (it’s very uncommon for people to chat with strangers at the bus stop, for example), but for some reason they become familiar with each other really fast in new school classes, like start talking about going to parties together after 20 minutes and such things (and of course those persons are usually girls ).
But then again people are different, so there is always at least a few super-social people in every big group who sort of take charge in everything.
But yeah, the normal greeting is basically introducing yourself and shaking hands with the person, and usually chat for a while.
Greeting somebody is kinda complicated in Iran. Between women, 2 or 3 cheek kisses are usual, depending on the family. Between men, they usually handshake. Between men and women, it really depends on how religious they are. Non-religious people will shake hands, while religious people will kinda bow their heads towards each other. Men will usually put their right hand on their chest while they do this. If the man and woman are close - for example grandma and grandson, they will do cheek kisses as well. Cheek kisses are not formal though, even for women. Only between friends, family, etc. In formal places, women shake hands with other women and men shake hands with other men. In most formal places women and men will not shake hands.
In general, I’d say Iranians are very… could I say friendly? towards strangers. I know in some cultures, strangers don’t really talk to each other randomly. But in Iran, if you ride a bus or sit on a public bench or something, the other people will talk to you as if they’ve known you forever. Sometimes it can be very nice, but sometimes it can make you feel like they are nosy 
Strange women are addressed as “khanom” (ma’am) and strange men are addressed as “agha” (sir), even in informal situations. Some extremely religious people may address each other as baradar (brother) or khahar (sister), but this isn’t common at all in Iran.