Friendly Kissing
I found this interesting to share with you guys 
Face-to-face Woman+Man Kissing to say hello is reserved for good friends only. Kissing to say goodbye is more common and can be done by most friends. Kissing during the conversation is too forward and should be avoided, UNLESS some very good or very bad news arrives OR you trust each other a lot as friends. One kiss on the cheek from both people, or two kisses from both people (one on each cheek) is polite. Always kiss on the cheek, never anywhere else, especially not on the lips - that’s too forward. Nowadays a kiss on the hand is also considered too forward and should be avoided. Woman+Woman Kissing is often more common than with Woman+Man. Kiss to say hello and goodbye, although hello-kissing is still not as common as goodbye-kissing. During the conversation should be reserved for good friends only, but can be done. Again, one or two kisses is fine, and kissing on the lips is also fine, BUT two kisses on the lips is often considered too forward. Stick to the cheeks and lips, anywhere else is a no-go area. Man+Man This is rarer, and should only be reserved for very good friends in any situation. Only kiss hello if you haven’t seen each other for ages, and only kiss goodbye if you’re leaving each other for a long time. Kissing during the conversation is forbidden unless very good or very bad news comes up. Never give more than one kiss per conversation, and only ever give it on the cheek. It’s wise to make kissing more discrete than with Woman+Man or Woman+Woman. In informal letters There are two ways to kiss: by writing the letter x at the end of a letter, and by saying something at the end of the letter. If you’re writing the letter x, then these x’s are a sort of short cut for writing other things, they’re like abbreviations. How many you write and what sizes they are gives varying effects. Keep the kisses small… about the size of a small x. Woman+Man x = “I’m happy to know you.” xx = “We’re fairly good friends.” xxx = “We’re very good friends, I like spending time with you and I think you’re a great person.” xxxx = “I like you a lot, you’re an amazing person and one of my best friends.” xxxxx (or more) = that’s too many, avoid doing this. No kisses is acceptable, and is still as polite. It’s up to you. However, if someone write you kisses and you don’t respond then that’s sometimes seen as rude. If you are saying something at the end of the letter, then this usually has the value of between xx and xxxx, depending on what you write. For example, “Kisses from Sheffield, I hope to see you soon, ~Tom” would rate usually between xx and xxx. If you put x’s AND you write something, the effect is cumulative. Don’t go over xxxx though. Woman+Woman x = “We know each other fairly well.” xx = “We’re friends.” xxx = “We’re good friends, I enjoy spending time with you.” xxxx = “We’re great friends, I want to spend a lot of time with you and I think you’re a really good person.” xxxxx (or more) = Keep this for best friends only, otherwise avoid. I’d recommend sending at least one kiss per letter, to not do so would be inpolite. To not return kisses is considered rude and should be avoided. Saying something at the end of the letter has got about one x LESS of an effect than with Woman+Man. Man+Man x = only use for distant members of your family xx = only use for closer members of your family xxx = only use for closest members of your family xxxx (or more) = avoid. Only send kisses to family, to send to friends is impolite. Try and stick to x’s, avoid making comments about it. In informal emails There are five ways to kiss: x, X, * and by writing something at the beginning or at the end of the email. X has roughly the strength of xx, and * has not quite got the strength of a single x (because it’s sometimes unclear whether the * stands for a kiss or not). Writing comments at the beginning of the email have roughly one x less strength than those comments would at the end. Comments at the end have about the same strength as they would in letters. If the recipient is over 30, it’s often wise to halve the number of kisses being sent. Woman+Man x = “We know each other.” xx OR X = “We’re friends.” xxx OR xX OR Xx = “We’re good friends, I enjoy being with you.” xxxx OR xXx = “We’re very good friends, I want to see you again soon.” xxxxx (or more) = avoid. No kisses is seen as impolite, but acceptable. Always return kisses that you are sent. Writing comments at the start or end of emails is fine. Woman+Woman x = “We know each other.” xx OR X = “We’re friends.” xxx OR xX OR Xx = “We’re good friends, I enjoy being with you.” xxxx OR xXx = “We’re very good friends, I want to see you again soon.” xxxxx, xxxxxx, xxxxxxx up to about xxxxxxxxxx OR any X in place of any x in these cases = “We’re best friends, I really like spending time you, I think you’re amazing.” xxxxxxxxxxx (or more) = avoid. No kisses is seen as impolite. Always return kisses that you are sent. Writing comments at the start or end of emails is fine. Man+Man x = “We’re friends.” xx OR X = “We’re good friends, I enjoy being with you.” xxx OR xX OR Xx = “We’re very good friends, I really enjoy being with you.” xxxx (or above) = avoid. No kisses is fine and acceptable, BUT always return kisses that you are sent. Writing comments at the start or end of emails is fine for good friends only. In SMSs There are four ways to kiss: x, X, * or by saying something at the end of the SMS. As with emails, X carries roughly the strength of xx, and * carries not quite got the strength of a single x (because it’s sometimes unclear whether the * stands for a kiss or not). Comments at the end have about the same strength as they would in letters and in emails. Because SMSs are often sent many times in a conversation, kisses can only be used in your first SMS of the conversation, or your last SMS of the conversation. NEVER kiss in more than one SMS in the same conversation, unless it’s to kiss goodbye once you’ve already kissed hello. If the SMS is the first one you are ever going to send to the person, then it is polite to add at least one x to it. If the recipient is over 30, it’s often wise to avoid SMS kissing altogether. Woman+Man x = “We’re friends, it would be nice if you SMSed me back.” xx OR X = “We’re good friends.” xxx OR Xx = “We’re very good friends, I’m waiting for your reply and I want to see you soon.” XX = “We’re very close friends, I can’t wait to see you again. Please reply.” xX OR xxxx (or above) = avoid. (The reason for Xx or XX being fine, but xX being unacceptable, is that you have to put some effort into writing xX on a mobile phone, but less effort for Xx or XX. Friendly kissing is meant to be effortless - even though the way I’m explaining it to you now makes it sound like the opposite!) No kisses is seen as impolite, but acceptable. Always return kisses that you’ve sent. Writing comments is fine. Woman+Woman The same applies as for Woman+Man. Man+Man x = “We’re friends, it would be nice if you SMSed me back.” xx OR X = “We’re good friends.” xxx (or above) = avoid. No kisses is seen as impolite, but acceptable. Always return kisses that you’ve sent. Avoid writing comments.
how about xoxo? thats more common than any number of x. Also, in different cultures, differnt kissing is appropriate. Russian men kiss each other on lips 
, latins kiss and hug with no end and for no reason, etc…
ok, i forgot to say that this is mainly in UK. i know about different cultures. in winter, when i was in lisbon e.g., and when i went to the church i was surprised when i had to kiss poeple at the part where everyone wishes peace to each other…