I am getting fatter and fatter. My classmates are always laughing at me.
My father always smokes at home.
My best friend forgot my birthday.
My father's birthday is coming. I don't know what to buy.
You should (do) ...
Maybe you could (do) ...
Why not (do) ...?
Why don't you (do) ...”
What about (doing) ...?
How about (doing) ...?
Would you mind (doing) ...?
You had better (do) ...
If you ..., you'll (do) ...
I've known your problems. Here is some advice that may help you. First, if you are getting fatter and fatter, I think the best way is exercising more every day. Don't eat junk food. Eat more fruit and vegetables. You must be very upset when your classmates are laughing at you. Don't mind it! Everybody has strength and weakness.
Everybody knows that smoking is bad for health. If your father smokes at home, you should have a talk with him. Try to help him give up the habit. If it is too difficult for him to give up the habit, you should ask him to smoke outside instead of at home.
As for your father's birthday party, what about holding a surprise party for him? Write some wishes on paper. Then make some paper planes. Throw the paper planes when he comes into room!