One way of telling people what they should do is to use the phrase I think you should…
I think you should consult a doctor.
I think you should change jobs.
I think you should get that car repaired.
I think you should accept that job.
I think you should consider that offer.
I think you should talk to her.
To make a more direct suggestion, you can use You should…
You should mend your ways.
You should be more responsible.
You should stop smoking.
You should find a better job.
To suggest what someone else can do, use the phrase You could…
You could talk to him.
You could ask him to help you.
You could borrow some money.
‘What shall I do tomorrow?’ ‘Well, you could go for a swim.’
When you’re in Chennai, you could go and see Malini.
If you want to do something, you can say Let’s …
Let’s go for a walk, shall we?
Let’s watch a movie.
Let’s buy something to eat. I’m starved!
Let’s ask their opinion.
Let’s wait for some more time.
Let’s buy some flowers for her.
If you want to make a suggestion and see if other people agree with you, use Shall we…?
Shall we buy something to eat?
Shall we go for a walk?
Shall we take a break?
Shall we ask Madhuri if she wants to come with us?
Shall we buy a new car?
Another very common way of making suggestions is to use the phrase How about…?
How about buying something to eat?
How about watching a film?
How about going for a drive?
How about taking a short break?
How about sending him a message?
How about renting a car?
How about asking his help?
Note that a verb used after How about…? should be in the –ing form.