Highly recommended YouTube channel! Learn about veganism, what it is, arguments for it and against it, by watching various debates from this logical mastermind!
The best way to do it is to try pursuing diplomatic options. If all else fails, of course, defend yourself & others. Though most issues can be resolved with words, or intimidation if necessary. The latter might require some martial experience though & should not be done lightly. Again, focus on diplomacy. There are many books & teachings out there and show ways avoid violence without coming out on the wrong end of things.