Sometimes it isn't possible to avoid a narcissist. My advice has consistently been to cut off contact with narcissists because of the futility of trying to have a relationship with these debauched and predatory types with the wizened soul of a demon. Unfortunately, sometimes you can't avoid dealing with a narcissist. This is often the case when you work for one. If the narcissist is a family member, perhaps you aren't willing to cut them completely off because you have successfully minimized contact. Fact is, we sometimes have to find ways to get along with a narcissist while still trying to maintain some boundaries. To successfully accomplish this one needs some tools. These tools come from recognizing the primary motivations and world view of the narcissist.
Here is a link to a PDF article by Steve Becker, LCSW, CHT...a psychotherapist. The article is titled, "Communicating with Narcissistic Personalities".
Another interesting article at his site is here and is titled "Differentiating Narcissists and Psychopaths". Both articles seem right on to me.
A thought I have about differentiating between narcissists and psychopaths runs along this line. The fact that we need some help to tell the difference tells me that the differences are small. In practical reality, the effects of the behaviors of the two are essentially the same. It matters not whether you are dealing with one or the other...both will wreak the same types of destruction in the lives around them. So what if the narcissist has a need for validation and some remnant of a conscience left when the psychopath doesn't? When it comes down to the nuts and bolts of living life, the fact that you can't usually tell between the narcissist's and the psychopath's underlying motivations because their outward behaviors are essentially identical tells me all I need to know. I would never knowingly keep a psychopath in my life because they are dangerous. A narcissist is rarely any less dangerous to life, health and wealth. Said another and simpler way: both are personifications of evil. Both are dangerous.
The fact that we need a primer on how to tell the difference between two types of evil tells us we would be wise to distance ourselves from either form. One is not less evil than the other. They are simply variations on a theme. Two points on a continuum.