Here are some word, phrases and expression to convince others
1. Why don't you try our special drink to warm up your body?
2. If I were you, I would.......
3. I am sure you are on the right track
4. I bet you could do it better
5. I believe that is the best decision, etc
Now bellow is an example of short dialogue using expression to convince your friends due to the representative of the class in English speech competition
John: There will be English speech competition in my school
Tom: So what?
John: My friends appoint me the representative of the class
Tom: That is great
John: The problem is.....
Tom: What is the problem?
John: My English is not quite good
Tom: Your English is on the track. The grammar, structure, pronunciation, what else?
John: I am not so confident
Tom: Why not? I bet you will be one of the winners
John: Ok, if you think so. I will prepare myself for the competition
Tom: That is the best decision and that is my best friend