In fact native speakers use the subjunctive in English less and less. But in the past they used it much more to talk about possible, desirable or imaginary situations. These days they are more likely to use modal verbs such as 'should' or 'would'.
However, we can still use the subjunctive in certain situations:

Firstly, it is sometimes used in 'that' clauses after certain words (e.g. suggest, recommend, advise, insist) to express the idea that something is necessary or important. For example:
I recommend that he begin a course of treatment immediately.
The judge insisted that she give evidence in court.

Now this use is more common in American English than it is British English. We can also use the subjunctive of the verb 'be' after 'if' or 'I wish' with 'I' and 'he/she/it'. For example:
I wish I were young again.
If I were you, I'd use it while you have the chance.

And finally, we still use subjunctive forms in certain fixed expressions, for example:
God save the Queen.
Be that as it may, we must make savings.
If he decides to leave me, well so be it.