Formal:
* स्वागत है (Swagat hai): This is the most common and formal way to say "welcome."
* आपका स्वागत है (Aapka swagat hai): This is a more polite version of the previous phrase, literally meaning "your welcome."
Informal:
* आओ (Aao): This literally means "come," but is used as an informal way to say "welcome."
* आपका स्वागत है (Aapka swagat hai): This is also acceptable in informal situations.
Other options:
* शुभकामनाएं (Shubhkamnaye): This literally means "best wishes," but can be used as a more formal way to say "welcome."
* हार्दिक स्वागत (Haardik swagat): This means "warm welcome" and is a very polite and respectful greeting.
The best option for you will depend on the specific situation.