what is the best way to teach english grammar?

the best way in my opinion to teach English grammar is to try always checking examples from texts related to the assessed unit

Contextualize.
Find or create a text with your target language.
Write an example sentence from the text and ask your learners to underline similar forms.
Ask some check questions to check meaning; then you can focus on form.
Finally, give your learners some controlled, then freer practice.