Dealing with Antis is always a challenge. I have found it best to listen to them first, as hard as it is, and then lead them with questions to help point the way. There's an old saying that questions lead, and answers follow.
Usually the antis start off with the precept that 'guns are dangerous'. The questions to ask depend on the person you are dealing with, but some comeback questions are: "well isn't gasoline?" or some other 'dangerous thing'. The logic flows well from there - well gasoline has other uses other than killing and it's well controlled. Then you can proceed to discuss how firearms are used every day for self defense, target shooting and hunting. The defensive uses are estimated at over 2 million times per year. Another comeback question might be along the lines of "how do you keep something dangerous in the home?" You can then educate about responsible gun ownership and gun safety. You can also discuss the laws that are already in place to keep all the law-abiding citizens in line that criminals ignore daily. It helps to have some recent info on murders and violent crime in the local areas. The FBI uniform crime report is a source for total view, you can Google that or your local state (PA?) and armed robbery, home invasion, etc... I find once I point out that there are plenty of home invasions, with armed intruders in multiple incidents, people wake up pretty quick to the risk.
Sometimes it goes like - "well we need to keep them out of the hands of criminals". The questions then should be along the lines of "are criminals allowed to have them?" And you can drive it further that they are already law breakers and will kill or attack with an axe if they can't get a gun. If you want to really make a dent in crime - look at the CCW stats, where violent crime goes down uniformly whenever CCW is passed, because the criminals don't know who is armed. Same argument about why criminals are often long term offenders that get let back onto the streets too quickly and too easily. The point being made that the antis and us should have in common is anti-crime, not anti-guns.
Well not a comprehensive answer but I hope that helps get you started. As others have said, John Lott's books are a good starting point for stats and logical arguments.