It's so hard to be nice sometimes. Wish English-speaking actors "Good luck!" and it's as if you'd brought the curtain down on them rather than told them to bring the house down. You have to say "Break a leg" - which, incidentally, some linguists believe comes from the German phrase "Hals und Beinbruch" ("neck and leg fracture"), which in turn could derive from the Yiddish "hatsloche und broche" ("success and blessing"), a version of the Hebrew "hatzlaha u'vracha." Talk about the whole world being a stage.
You would in fact wish an Israeli actor "Behatzlaha" before a show if you didn't want this to be their final act.
Behatzlaha is indeed far more useful than the mazel tov (literally "good luck") Diaspora Jews are brought up saying. It's not enough to remember to change the pronunciation of the first word to "mazal," you have to remember that this word is used more for congratulations than wishing someone success in an endeavor.
Weddings are one of the few occasions when the mazal tov is still appropriate. The common (and oh-so-typical) response, if the well-wisher is himself single is, "Bekarov etzlecha!" This is usually translated in "Jewish English" as "Please God by you," but literally, "Soon by you." By association, the sound of breaking glass anywhere, not necessarily under the wedding canopy as part of the traditional nuptial ceremony, is also accompanied by "Mazal tov!" There is no appropriate response to the well-wisher in such cases. Definitely don't try a "Bekarov etzlecha."
Colloquial Hebrew is full of different greetings for various occasions.
Bought something new? Guys will be wished "Tit'hadesh" and gals "Tit'hadshi" (literally, "renew"). This applies to anything from a refrigerator to a new shirt. Except, and there are exceptions in any language, in the case of new shoes. Then, you happily walk off with the wish "Tevaleh/tevali" ("Wear them out!") ringing in your ears.
The long and the short of greetings for a new haircut is "Sapihes," possibly derived from the word "tchap'ha," a slap on the back.
A slap on the back between friends is often accompanied by the wish "Ta'aseh/ta'asi hayim!" (literally: "Make life!"), a more common version today of "Bilui na'im" (lit. "Pleasant entertainment," used for "Enjoy yourself").
New IDF recruits naturally march to a different tune. They are seen off with the wish "Shifshuf kal vena'im" (literally: "Easy and pleasant rubbing"), which seems to refer to the blisters that are as inseparable a part of basic training as the sergeant's orders. No amount of wishing "tevaleh" will make the average army boot fit the foot of the average military rookie.
Taking a break from it all? You should be wished "Hufsha ne'ima" ("A pleasant vacation") or Nesi'a tova ("Bon voyage"), one of the occasions when the French have a word for it but not the British. For a shorter journey, the greeting "Derech tzlecha" should put you on the right track.
Another cue from the French: In Hebrew, Bon appetit! is "Be'te'avon!" (literally "with appetite"). The only time "Be'te'avon" does not go down so well with food is during the Mimouna, the holiday almost unknown in the English-speaking Diaspora, which falls the day after Passover. Then you need to practice saying: "Tirbehu vetis'adu!" the traditional Moroccan Jewish greeting for the festival.
If you want to drink to that, a "Le'hayim!" is in order - one of the few greetings you can safely bring with you on aliya when arriving as a new immigrant. Yishar ko'ah, a Jewish version of "more power to you," often used in synagogues, is another (but check out your pronunciation. Hebrew and Yiddish ["Shkoyech!"] often say the same thing very differently).
Some Yiddish greetings have traveled the world. I treasure the memory of the time I sat down - miserable with a cold - in a Hong Kong restaurant called New York Deli. In a scene that could have come out of a Mel Brooks movie, the very Oriental waiter passing my table as I blew my nose wished me "Gezundheit!" It turns out that the Hong Kong native really had worked in a New York deli for years and his Yiddish was not to be sneezed at, as it were. (The Hebrew, which would have made me feel right at home, is "Labriut!" "to health!")
Had I not been speechless, I should have probably responded "Bravo," or as they say around this tiny part of the world: "Kol hakavod."