Bl. John Henry Cardinal Newman's Apologia Pro Vita Sua is a model of how to respond charitably to falsehoods. And St. Thomas More, St. John the Baptist, and Sts. Peter and Paul will help us learn how to speak Truth to power, even when we would very much rather play it safe. The hard reality, I think, is that what we tell the world about Jesus' Church has never been popular--lessons we've all clearly learned in our own lives.
A practical tactic that I've found helpful: Joe Scheidler's Pro-Life Action League in Chicago publishes a wonderful little book called Sharing the Pro-Life Message that indexes all the pro-abortion arguments and the corresponding pro-life counter-arguments, exhaustively researched and footnoted. If you go to prayer vigils at abortion mills, you will be accosted and insulted, but the good news is (at least) threefold: 1) This is great practice in answering nastiness with love; 2) The "arguments" you will hear will almost always be the same tired, false, hard-hearted, illogical stuff--you'll very quickly become adept at swatting those arguments down; and, 3) You will be a vehicle for the Holy Spirit (I've witnessed miraculous turnarounds when speaking with people I never would have thought God could reach).
Beyond pro-life work, the Catechism of the Catholic Church is a treasure trove of the riches of our Faith. We have no idea of the inexhaustible bounty we're sitting on... If folks really understood Catholicism, they wouldn't hate it (unless they were actively Satanic, which is certainly a possibility). Every criticism, then, is really an invitation to evangelize. And the CCC is just waiting to be opened and shared.
I grew up in the Deep South (which I love), surrounded by fiery Baptists--not a single one who ever criticized my Catholicism had any idea what they were talking about, but that doesn't mean their ignorance has to be permanent... There are a lot of good, God-fearing Protestant Christians out there who deeply love Jesus--that means God's already done all the hard work for us, and they're probably more open to the Truth than they might realize.
Admonishing sinners, counseling the doubtful, instructing the ignorant, bearing wrongs patiently, and forgiving transgressions are all spiritual works of mercy. The Holy Spirit will give us the Grace to witness to God's unchanging Truth--and it will make us holy in the process!
Bl. Cardinal Newman, St. Thomas More, St. Peter, St. Paul, St. John the Baptist, St. Jerome, St. Irenaeus, St. Augustine, Ora Pro Nobis.