In my opinion, common everyday narcissism means having a noticeably greater amount of self-interest and insecurity than empathy and confidence. If there was such a thing as an ideal personality, you’d have the capacity for both in roughly equal measures.
To see something of what it feels like to be narcissistic, start by saying to yourself that you can’t afford to care much for the well-being of others who are close to you. If you do, you’ll threaten your ability to survive and get what you need out of life. Of course, you’ll have to pretend to have some heartfelt concern for people and learn the right things to say. You also need to hide your deep feelings of insecurity by acting in a somewhat arrogant or controlling fashion. Think of a characteristic, right or privilege you have that you can use to give yourself the feeling of entitlement to a position of power. It’s important not to let anybody get too close to you and figure out that you feel largely empty and scared inside, so you might want to adopt some bullying characteristics. Pretty much, it’s safe to let another person have something on the order of an intimate relationship with you if and only if it feels like he/she is part of you. You’ll have increasing trouble with this individual as your differences and challenges show up.
At the end of the day, it’s pretty lonely to be narcissistic; you feel misunderstood and threatened a lot. You have to do a fair bit of pretending to pass as someone who is caring about others. Often, you need to resort to being manipulative or controlling to manage your situation.
There’s a huge difference between a tendency towards narcissism and a narcissistic personality disorder.
Consider my description above, which gives you some idea of narcissism. If you have some inclinations to be like that and/or certain situations bring it out in you, you’re using it as a means of coping. And, who knows? Maybe it’s a good way to be in your circumstances; it could allow you to survive and/or thrive. Plus, consider what you want out of life and whether or not being like this meets your needs.
A narcissistic personality disorder needs to be diagnosed by a mental health professional charged with that responsibility. Part of the criteria is whether or not this is a rigid personality structure that is difficult to change. Not only would these characteristics show up across the board but also they would represent who you are whether or not they serve you well. Plus, rather than having some tendencies towards a few characteristics, you’d more or less have many of them in spades.
If we’re looking at tendencies towards narcissism, consider these questions: Can he/she understand an emotional experience he/she hasn’t had? Is he/she actually operating in your best interests or in his/her own? Do you have the feeling that this individual is taking advantage of your weak spots? If you restrict eye contact, does it make it harder for him/her to do so? Do you have a weird feeling of inner conflict around this person? Do you feel sorry for him/her, as a child who hasn’t grown up and gotten past the stage of just thinking about him/herself?