Formal:
* 欢迎 (huānyíng) - This is the most common and general way to say "welcome."
* 欢迎光临 (huānyíng guānglín) - This means "welcome to our place" and is often used in businesses or shops.
* 欢迎回来 (huānyíng huílai) - This means "welcome back" and is used when someone returns after being away.
Informal:
* 你好 (nǐ hǎo) - This means "hello" but can also be used as a casual way to say "welcome."
* 进来 (jìnlai) - This means "come in" and can be used as a way to invite someone in.
Other:
* 热烈欢迎 (rèliè huānyíng) - This means "warm welcome" and is used for more special occasions.
* 欢迎参加 (huānyíng cānjiā) - This means "welcome to participate" and is used when welcoming someone to an event.
The best way to say "welcome" depends on the situation and your relationship with the person you are speaking to.