How to make a question or suggestion sound more polite?

In English we use certain structures to make a request, question or
statement sound less direct and therefore more polite.

By using past tenses

Past tenses are often used to do this because these verb forms suggest
‘distance’ from the immediate present reality.

How many days did you intend to stay, sir? (= How many days do you intend to stay?)
I wondered if you could lend me some money?

The use of the past tense in the above questions make them more polite.

Progressive verb forms are also used to make a question or suggestion sound
more casual and less definite.

I am hoping you can lend me $50. (More polite than ‘I hope you can lend…)
We are looking forward to hearing from you. (More casual than ‘We look
forward to hear from you.)

Past progressive forms make questions and suggestions sound even more polite or less definite.

I was wondering if you could lend me $50.
Were you looking for anything special, Sir? (More polite than ‘Are you
looking for anything special?’)

By using future tenses

Future tense forms can be used to soften instructions and orders.

I will have to ask you to wait outside.

Future progressive forms are often used to enquire politely about people’s
plans.

Will you be staying for long? (More polite than ‘How long do you intend to
stay?)