I know youve talked about it and ive read them all but Im still not totally clear

How much do we tip at a restaurant and how much at a buffer and how much at the bar

Im confused because Ive been told double the tax, 20% of the whole bill, 20% of the bill without tax, 15-20 with 25 if good

I've been told at a buffet it's 10% but then the card that comes with the bill says 15-20 or it did last time

I've been told $1 a bag for the people who bring the luggage but then other people say $2 or $10 minimum if it comes to less than that!

What about people outside the hotel who just open a taxi door for us? do I have to give them dollars? and if so, how do I tell them to just leave it I'd rather open the door formyself and save my money for the mall

See what I mean its all confusing