Good morning! Good afternoon / day! Good evening! Good night! Hello! Cheerio! So long! Good bye! See you later! Good luck! A pleasant journey!
Last, but not least... favorite informal greeting: Bog! (prononunced from "boK" to "boG" in in different parts of Croatia)
Merry Christmas! Happy New Year! Happy birthday! Happy holidays! Congratulations! Thank you, the same to you!