Wah How to use "Supposed to".

We can use supposed to to indicate obligation.
We usually use this form in an unfulfilled or angry way.

Be + Supposed to + Verb

It is similar to should and ought to.

• You are supposed to be at work. (You should be at work.) 
• You are not supposed to smoke here. (You should not smoke here.)
• I am not supposed to be here. Please don't tell anyone.
• You are supposed to introduce yourself.
• Are you supposed to know that? 
• What am I supposed to do?

We can use supposed to to indicate obligation in the past.

• I was supposed to go to work yesterday. (But I didn't.)
• How was I supposed to know that? (No one told me about that.) 
• You were supposed to clean your room.
• He was not supposed to tell you.
• Sally was supposed to meet her friend last night.

They are supposed to study hard for the exam tomorrow.

Wah How to use "What about...?"

1. We can use What about to suggest someone to do something.   
    I don't want to go to the library, what about going to the movies? (Let's go to the movies.)
    Rather than waiting here, what about going around? (It's better to go around.)
    I don't feel like working now, what about going shopping instead?
    I am on diet, what about having fruit salad for dinner?

You also use How about. They have the same meaning in making suggestion.
    How about coming with us? (Shall you come with us?)
    Rather than going to the cinema, how about the theater? 
    The traffic is very bad, how about getting there for a walk?
    Your brother is mad at you, how about apologizing your brother?

Wah How to use "Make Sure"

If you want to give the instruction or advice to another person, you can use Make sure + Clause.

Make sure means “be sure”, “be certain”.

      After using the knife, please make sure you put it back where it was.

      (After using the knife, please be sure to put it back where it was.)

      You've got a cold; make sure you bring some medication.

      It’s very cold outside; make sure you take a coat.

      You are going shopping; make sure you have enough money.

      If you will be camping in the forest for week; make sure your health is ready.

      If you are going to drive long distance; make sure your car has no any problems.

Sometime you can use auxiliary verb before make sure;

      After using the knife, you’d better make sure you put it back where it was.

      It’s very cold outside; you should make sure you take a coat.

“And I will make sure to keep my distance

Say, "I love you," when you're not listening

And how long can we keep this up, up, up?”

From Christina Perri ft. Jason Mraz – Distance