请。

Put 请 at the very beginning of a sentence. It works like a prefix for actions. If you want someone to sit, say 请坐. If you want them to enter, say 请进. It is simple, punchy, and effective. You do not need complex grammar to sound like a pro.

Use it whenever you need something from someone else. Use it at a restaurant when ordering your spicy noodles. Use it in a taxi when giving directions. Use it when meeting your partner's parents for the first time. It is even great for texting when you are asking a quick favor. It turns a command into a polite suggestion.

Do not use it with very close friends for tiny things. If you ask a best friend to pass the salt, 请 might sound too distant. It can feel like you are putting up a wall. Also, do not put it at the end of a sentence like in English. Saying 'Help me, please' translates to 请帮我, not '帮我请'. That would just sound confusing!

Chinese culture places huge value on 'mianzi' or face. Using 请 gives the other person face. It shows you recognize their effort. Historically, it relates to the concept of hosting and hospitality. Even if you are just asking for the time, you are 'inviting' them to help you. It is a small word with a long history of social harmony.

If you want to be extra fancy, use 请问 to say 'Excuse me, may I ask.' If you are paying for dinner, say 我请客. That literally means 'I invite the guest,' but everyone knows it means 'It is on me!' You can also use 请求 for a more serious, formal plea. But for daily life, the single character 请 is your best friend.