I always address these lies society put in people's heads about Metal first. I also play easier or more accessible (like Paradise Lost), not overly complicated (like UDO or Accept) stuff around them not to alienate them 'cos I can perfectly understand bands like Carcass are almost impossible to like on first listen especially if you haven't listened to any other metal yet. Or sometimes I would utterly confuse them by playing a band that is harsh and rough at one point, and seriously melodic at other points. Rage is great for this.
Oh, and Iron Maiden. Almost everyone likes Iron Maiden, they're a good band to get people into the genre. Though the best way, and I really mean this, is the bands I call stepping-stone bands who have kinda broken into mainstream, some of them pseudo-metal bands. After a while people who listen to this stuff would get in touch with more real metal 'cos they realize there's more than they know and they outgrow the more mainstream-orientated metal bands (not saying all of these are bad, far from it and I believe they serve their purpose, many metal fans are simply too paranoid about anything that breaks into mainstream). Getting into metal takes time for most people, especially for the more extreme sorts. Hell I know I had to play Paradise Lost's Gothic 6 times before my ears were able to hear how good it was.
Since metal has blended with almost every other genre out there it's also always possible to find a band who mixes a genre they like with metal. For example a blues fan could like early Black Sabbath, rap / hiphop fans could like Disturbed. You can then borrow them an album, though I recommend copying one.
Honestly I don't really care that much about 'recruiting' people, though it's definitely fun when fe my dad starts playing my Fear Factory or Dio records. I just expect nothing and I've noticed that when you simply open a door for people to discover something for themselves they are more prone to like them than when you put a band up their face and tell them it's good likely because they can feel more like it is 'their' band then than when someone else has introduced them to it, you see.