Kindly reference the following links:
How to advise people who don't pray on time & sometimes pray after time is over? - Assim al hakeem (being harsh in dawah)
Masjid filled with people without beard, must I advise everyone? (establish relationship before giving dawah)
Being afraid of being called The Haram Police while enjoining good and forbidding evil?
Also see: Enjoining Good & Forbidding Evil vs Poking your nose in other's affairs KB