Formal:
* བཀྲ་ཤིས་བདེ་ལེགས་ (Tashi Delek): This is the most common and polite way to say "welcome" in Tibetan, used in formal settings or when addressing someone you don't know well. It literally translates to "May good fortune and happiness be upon you."
Informal:
* ལྷག་པ་ (Lhagpa): This is a more casual way to say "welcome" and is used in informal settings or when addressing someone you know well. It literally translates to "welcome" or "come in."
So, choose the appropriate greeting based on the situation and the person you are greeting.