1 Know your objective. Pronunciation is about being understood by people all over the globe. It’s not about pretending to be American or British. You don’t need to teach every small detail of the way they speak in the US or UK – very few learners will ever learn that, and there is no reason to anyway. English is a world language now – it doesn’t belong to any particular country.
2 I’m OK! Say that to yourself. Teachers sometimes feel they aren’t a good pronunciation model because they aren’t ‘native speakers’. That’s not true. If you are an intelligible speaker of English, you are a perfect model. When we think of English as a lingua franca, the term ‘native speaker’ no longer makes sense – we are all native speakers of it!