Amr bil ma'roof and nahi anil munkir is indeed what is expected from a practicing muslim. However, while exercising this, one needs to take few things into consideration.
1. Exemplify yourself. It is far more effective than asking people to do or not to do something. Some religious parties are working for decades but people don't give them a heed, have you ever thought why? Because what they ask others to do, they themselves don't follow. People view them as hypocrite, and rightly so.
2. Charity begins at home, as the English saying goes, one needs to start among their closest ones. Who were the people Mohammed (PBUH) preached Islam to in the beginning? His wife Khadijah, and than he invited his closest family members, and than people from his clan, and so on. Why would you do this? Because chances are, they know you are talking to them in good faith. They will perhaps not get offended by your invitation, and like to give it a thought. Similarly, we need to coax our closest ones first, and than let them to invite their closest ones, and this way your message will spread. This is the logical way of asking people to do good things, and not the bad things. I can ask my son, I can punish him too if he does not listen to me, but can I do this to a stranger?
3. Respect other's views and ideas. You don't have to agree, but show tolerance. If Allah can tolerate people with all sorts of sins, and wrongdoings, and yet take care of them, who am I to do otherwise? Their is no compulsion in religion, we read it in Quran, but we never practice it.
4. A Hindu couple came to see a muslim saint (unfortunately I forgot his name) and offered him a glass of syrup. The saint was fasting and it was asar time. He promised with the couple that he will drink it at sunset. The couple insisted for they had to go back to their village. The saint took up the glass and drank all the syrup. The couple left happily. Saint's companions asked him why he did that? He replied to them (this warrants to be written in gold) "I am a healthy and well to do person. I can afford to fast for another 60 days or feed 60 poor as 'qasas', but I can't afford to break the heart of someone who brought something for me with such sincerity and passion. Next day, the Hindu couple came back and brought along many people from their village. They accepted Islam on saint's hand.
This is a true incidence and I will try to post the reference. You see what message is hidden in it?
Now my friend, you decide for yourself, what is the method of asking people to live their lives according to Islam. By what I described above, or by shoving down one's ideas down others throat?