Remember that you are probably the only representation of authentic Catholicism that they will likely come across. Live your faith but do it is such a way that you avoid what may cause scandal or offend. What I mean by "offend" is to be non-confrontational and to avoid insults, backhanded comments, etc. I believe that when priests had to dine in mixed company, where saying grace in an outward manner would offend, it was customary to bow the head quickly and discreetly before sitting for the meal. There is a time and place for everything, even discretion.
When I deal with heretics, I keep it secular. The office of preaching belongs to the clergy, so I feel I have no need to preach. Debating isn't an option either, as it puts truth and error on an equal level. Those authorized by the Church have already printed, with permission, books containing an imprimatur on apologetics, which I can cite or refer them to if necessary. Explaining and witnessing, totally, but there is a time and place. So that leaves me with a chance to practice charity and good manners, and I try to find common ground in matters not related to faith, if the discussion of matters outside of a task at hand are necessary.
I deal with Protestants, a lot, on a social level. In some cases I have been able to present the view of traditional Catholics and it has been well received. In all things, I try to point them in a small way towards anything that would be a step closer to the Faith. Keep in mind that God wants us to live according to our state in life, and for married women it means being gracious and graceful, not a missionary. :cheers: