If you're traveling to Mexico it is not really an issue of you speak Spanish. Most of the Mexican people speak at least a little English -- especially in all of the hotels and restaurants. So even if you've forgotten the Spanish you learned in high school or haven't mastered Rosetta Stone, there are a few things it is nice to know how to say.
"Thank you" -- "Gracias"
"Please" -- "Por Favor"
"No entendo" -- "I don't understand"
When sellers are pushing their wares on you, and they will -- say:
"No tengo dinero!" -- "I've got no money!"
They will never believe you but you can say it anyway.
"How much?" -- " Cuanto questa?"
"Good morning" -- "Buenos Diaz"
"Good evening" -- "Buenos Noches"
