Buying a train ticket - language points

Making polite requests.

I would like... to buy / ...to know

I'd like... to see / ...to try / ...to take

I'd like to try this blouse in a size 12 please.

I'd like to take this one please.

I'd like to know where I can buy a bus ticket, please.

Asking polite questions.

Could you...

...tell me... where / how / what / which

...help me

...show me... where / how

Could you tell me where the police station is, please?

Could you help me please? I'm completely lost.

Could you show me where the men's shoe department is, please?

Could you show me how to use this, please?