A few tips - what they should do
Learn a couple of broken arabic, as greeting formulas, thank you, very much, please, my name is. Your counterpart certainly dominates English or French as Lebanon is a multi-language country  - but nevertheless he would be pleased if you know a few words in his language.

On dinner invitations, note the Etiquette: the oldest eats as first. If you have eaten up, they will serve you again, so better leave something on the plate. The knowledge of European habits formed in circles does not mean that they can be adopted

So if you do not belong to any religion, occur in Lebanon as a Christian; chritian and muslims would expect it from you. The fact that someone doesn't belong to any faith community, is unthinkable and he will be scored as a shortcoming.

In Lebanon, the clothes tend to be more important than in our latitudesee Ensure also the external situation and the place where it is currently located, adapt, gives respect. Make sure you visit churches and mosques in conservative clothing, arms and  legs are to be covered under the knees, shorts and mini-skirts are off limit. In Beirut and especially in the hot season, many lebanese women bear shorter skirts and shorts. One feels less observed if the skirts and shorts, even in the capital, are at least up to the knees. In rural areas and muslim areas  (Baalbek, Sidon, Tyr and Tripoli), women shouldn't  have short skirts, shorts and sleeveless T-shirts. This applies, of course, for mosque visits, where also long pants for men are required.
For female tourists – by visiting a mosque, make sure you have always a headscarf in your case, but also get a long coat. When entering a mosque, pull the shoes  and remember God saying: "I am your Lord. Put your sandals off" (Qur'an Sure 20, verse 12; see 2nd Moses 3, 5). When you are inside a church or in the mosque, keep a quiet and inconspicuous behavior, in particular by prayer time. So basically you should never pass directly in front of praying, because you are so symbolically between praying and God. Avoid photographing people in prayer and in a very intimate situation - as anywhere in the world.

The cliché that Muslims feared by the photographs, will lose its soul.... this belongs in the realm of fantasy. But if we think  about what we would feel if we are photo motive for thousands of photo albums, we would understand them. In this case we better ask if people would like to be  photographed. By exchanging few nice words, this creates confidence and provides their picture in the album at home with a nice memory of the scanned people.

In Lebanon,  it is customary for people to welcome by shaking hands. People of the same sex often hug and kiss on the cheek. It is also the case in parts of the young, urban population, between men and women. Male travellers are welcome with a handshake, same for women in more traditional areas. Female travellers welcome women also by  handshaking, although welcoming can also happen by hugs and kisses on the cheek - a special sign of cordiality.

If you are a woman, that meets a man for the first time, wait for his handshaking. If he doesn't, then a short greeting and a smile as  welcome are enough. If a man doesn't shake your hand, you should not interpret this as a rejection, discrimination or discourtesy . The man sets, in this case, the rule that the men's and women's field (public and private space) are separated, and stricter than many others. Basically it is for females, compared with strange men always polite and somehow distanced, but determined and self-bility.

In Lebanon, it is unusual to exchange affection in the public space. Also, as a tourist, you are well advised to avoid  romantic kissing in public spaces.

A widespread stereotype claims that Arab men who go hand in hand, are homosexual. In truth, it is perfectly natural, and this is expression of friendship. Physical contact has a different status and is often fully understood and applied differently than we do.

The lebanese hospitality has a long tradition and is perceived by many travelers as ideal. Above all, individual tourists will find that they are always friendly invited. Here is tact and sensitivity required, because in spite of all the hospitality, it is not appropriate to accept any invitation immediately, as spending  days with a family or accept major favors. A general advice is difficult.
As a rough guide, it is recommended to signal a slight hesitation for accepting invitations. If then the lebanese repeatedly insists, then you can accept the invitation without misgivings.

If you deal with a family, so watch discreetly  the behavior of family members. The Lebanese population is limited by the different religions and traditions, this explains a general rule of conduct . In principle, one can say that initial reluctance, combined with easy friendship will open for you the doors to the Lebanese hearts.