Social kissing is becoming increasingly popular in Britain, but it is by no means an accepted norm, and is therefore a potential minefield.
To kiss or not to kiss? This is usually dependent on situation, age, background, profession and your relationship. As a general rule, don't kiss people you don't know. Don't kiss colleagues. Do kiss close friends and dates. The key is to make your actions clear to avoid embarrassing confusion.
Usually it's right cheek first, but prepare to change direction at the last minute. Pull back decisively (but don't be too abrupt) if you are just giving one. Be cautious with those you are less familiar with - two might seem over the top. If confusion occurs over one-kiss-or-two, take charge and go in for a second. Humour is useful in deflecting embarrassment over the meet-in-the-middle mix-up. Three kisses is definitely too many.
Just holding cheek against cheek feels insincere (air kissing with 'mwah, mwah' side effects has become synonymous with shallow superficiality) but there is a fine line between an acceptable peck and an overly affectionate smacker.
Cheek skin must make brief, light contact; sound effects and saliva traces are to be avoided at all cost. If you'd prefer to shake hands, be sure to hold yours out before any kissing manoeuvres begin but, if you're part of a group introduction, don't be the only non-kisser at the party.