Most functions follow a similar format to asking for information. They are normally introduced at a lower level and then revisited at higher levels to introduce the more complex variations. For making suggestions we start by using:
And then, at pre-intermediate level and higher, we introduce:
Why don’t you / we..?
If you think about it, giving advice and making suggestions have a big overlap. Often, when we give our advice, we are, by definition, suggesting to the listener that they should do something. At elementary level we introduce “should”. Giving advice is dead easy to practise. We often set up exercises where the teacher asks groups or pairs to advise them on a subject. For example:
Where should I visit in your country? Where should I go on my next holiday / vacation?
At pre-intermediate and above we introduce “ought to” and “If I were you I would…” It has been established that “ought to” is a little outdated and is becoming less and less used in everyday English. The issue is that our students will have to communicate with non-English speakers (in English) as often as with native English speakers. As many students were taught to use “ought to” in the past and not everybody learns from up-to-date course books then we need to also teach it.
It is okay to explain that it is not used so commonly as “should”; after all, we are trying to teach natural English.
“If I were you…” is a structure called 2nd Conditional. For this reason we rarely teach the structure as a function, but rather wait for the students to learn it as a grammar structure and then explain its use for giving advice.