Start cheek kissing on the left/right side

I am French and I never thought of which cheek should be first kissed! I don't think there is a definite rule. The protocol I identified is:

• first protagonist tends his or her cheek (left or right)
• second protagonist adapts and tends the same cheek.
• if it fails, both smile or laugh and the procedure starts again

As for the number of kisses, when people don't know each other's habit:

• one protagonist thinks it's enough and starts to stop the game
• the other one goes on playing
• both smile saying something about regional differences
• then they agree on either the short or long protocol

Cheek kissing - Wikipedia and How to air kiss - Wikihow gives conventions about kissing in diffrent countries, precising it's often the right cheek first.
("Air" kiss because your lips don't actually go on the cheek, it's more cheek-on-cheek and you make the noise with your lips.)

Only for France, combiendebises.com gives stats for each department about the number of kisses, and which cheek to give first (droite = right, gauche = left).
One can see that it's more often the left cheek in the south and the right one in the north.
(If you click on a department they ask you for the kiss count, which cheek goes first, your gender and which gender you kiss when you don't know the person.)

(There is also combiendebises.free.fr only for the number of kisses, but more voters.)

In the countries of the Levant (especially Lebanon, Syria, Jordan), cheek kissing is quite common. Depending on the situation, it might not be appropriate to cheek-kiss a member of the opposite sex.

However, in some areas such as the coastal part of Syria and most of Lebanon, or in case you're close friends or relatives, it's also common to cheek-kiss a member of the opposite sex.

The Lebanese cheek-kiss is performed by touching the cheeks and kissing the air. Starting with the left cheek, the right cheek, and ending with the left cheek, totaling 3 kisses.

The Syrian cheek-kiss starts on the right side, then the left side, in the last kiss that ends on the right cheek, a single more emphasized air-kiss or a double air-kiss is performed.

Update: Answering the question in your comment is not as easy to answer as one would think. As you probably have noticed in my answer, cheek kissing is common in places that were under the French mandate. In Lebanon the kissing starts on the left side. In Syria, Tunisia, Algeria, Morocco, the kissing starts on the right side.

Just keep in mind that the cheek-kissing isn't very deep in the Arab culture, so most people won't be offended if you start on the wrong cheek, you can consider it an ice breaker.

In Jordan cheek kissing always starts on the right cheek and moves to the left.

In the Netherlands, it's exactly 3 kisses, starting with the right cheek. Not between men.

As a man, it's absolutely not done to cheek kiss a woman who'd rather not, so you take a tiny bit of initiative and then see if the movement is continued, otherwise just shake hands. When in doubt, just shaking hands is always fine as well.

In Kuwait, Saudi Arabia (probably also Bahrain):

1. Close friends? left, right, left - this is the most common, air kiss.

2. Informal colleague? left only (of the person being kissed) along with a handshake. So you shake hands and give an air kiss on the left.

3. For close family relatives, air kisses between sexes is allowed; but its rare.

4. For elders (for example, your grandmother or grandfather, or the grandfather of your close friend), on their forehead, and its a kiss.

5. For elders, but you do not have the protocol to kiss on the cheek or the forehead, you kiss on their right shoulder. This is usually done when meeting someone of extreme prominence (like the Emir) and only by other Arabs, never by foreigners (who just shake hands).

In hungary we kiss each other on the left cheek which is contrary to lot of southern and western european countries. And it CAN cause a problem when your noses bump into eachother becase the other person starts with his/her right cheek.

For Catholics it is usually two kisses. Starting on left. So left then right. For Orthodox it's three kisses starting on right. So right, left, right. But kissing is always only for those who know you and who you know. Either close family or close friends. Anything other will likely be very offensive and intrusive. So don't just go around kissing people unless it's a joke and they know it's a joke. You might get yourself in trouble you don't want to be in. Otherwise people are pretty easy going for the most part. Obviously some are conceded assholes. So just use your best judgment.