one of the greatest ability a man should possess is the ability and courage to persuade people, yeah, individual or even a whole lot of people. persuasion might sometimes require some arguments before you could successfully achieve a great persuasion success and that;s why most people are so scared of facing a number of audience and tell them what they have to let them know,
persuasion is the ability to induce beliefs and values in other people by influencing their thoughts and actions through specific strategies, with this strategies, they may be convinced to adopt your own idea and drop the ones they actually believed in before if you approach them with full competence and really nice preparation, but don't forget some people have really fixed mindset, they are ready to zero all you said and won't always agree with you no matter how hard you try, you have to put that in mind, but don't worry, you can still do it, that is not enough to make you draw your back.
for example you are going to tell one of your friends who drinks to stupor until he always beats his wife and misbehave around his kids every night, what would you do? persuasion requires some processes and this processes could actually mean showing some proves that what you are sayig is actually the truth, in showing these proves, you have site examples, talk about people whom you know who actually are in this same shoes and didnt end up well, may be they lost all their families to the act, or something really bad happened, or tell true life stories , if you have had a very good character and the person in question knows well you are credible, you are trusthworthy, it will really help you to change is point of view,ultimately, your character creates the trust upon which you can build your arguement.
show that your intentions are real towards him, appear open-minded and sincere to him, always make sure to back up your statements with facts, with all these, your persuasion will go a long way.