Here are quick and easy tips to sound polite in English:

1. Use modal verbs. Modal verbs are used to talk about ability or possibility, they're also used to make your English sound softer and more polite.

Examples:
- Would you like to go for a walk? (vs Do you want to go for a walk?)
- Could you take the garbage out, please? (vs Take the garbage out, please.)

2. Use passive voice. This is useful in instances where it's rude to point out someone's mistakes.

Example:
- James forgot to lock the door. (vs The door wasn't locked.)

3. Use past tense. It is used to talk about things that already happened, but it is also used to sound more polite.

Example:
- Did you need help carrying that?

Hope these helped! Good luck with your studies! :)