The Do's and Don'ts of Friendship

Mark Matousek on how to be, find and keep a good friend.

Mark Matousek on how to be, find and keep a good friend

You know the friend who somehow saps your strength after every get-together? Or the one who perennially gives you a boost? How about the friend who feels like the sister you've always wanted or reminds you a little too much of the nosy one you've already got?

Our relationships with friends are critical to our health and happiness, and yet, they are often sorely appreciated or understood, says Mark Matousek, who distills the do's and don'ts of friendship in his recent book, "Ethical Wisdom for Friends: How to Navigate Life's Most Complicated, Curious and Common Relationship Dilemmas."

"Friendship is what sustains you when things get unruly with family and with lovers," even though we tend to prioritize friendship after these relationships, he says. Still, he points out that friendship is "very fragile" and "an affair of the heart." "All you have to do is lose one really good friend to get [that]," he says.

[Read: Harbaugh Brothers: A Healthy Sibling Rivalry?]

A writing teacher and personal development coach, Matousek's book is meant to provide a practical follow-up to his book "Ethical Wisdom," in which he looked at morality from a social and neurological perspective. Here, he tackles the thorny issues that threaten friendships, such as jealousy, competition and a lack of reciprocity.

So, what does it take to sustain a healthy friendship? Much of what makes any relationship work – trust, acceptance, respect and a balance of power, for starters. Below are five of Matousek's tips for more fulfilling friendships:

1. Identify your true friends. "Know who those people are who you can count on 24/7, who [are] really paying deep, close attention to you," and accept the distinction between this inner circle of comrades and those for whom you aren't a first priority, he says. Then, set your expectations accordingly. Know, too, that a Facebook friend does not a true friend make. "In the digital age, it's really important to remember, friendship is what's private and intimate and exclusive between you."

[Read: Facebook Post-Breakup: Bad for Your Heart?]

2. Live and let live. Don't try to fix your friend or his or her particular challenges – unless they are in physical danger. "Your job is to support them as best you can, to mirror back to them truthfully and compassionately what they're saying to you, but to be on a white horse and to try and save your friends' lives? No, that's self-righteousness, and that's not what friends do," he says. Matousek also warns against sharing judgements about a friend's spouse or relative. "When you trespass the sanctity of another person's romantic or family relationships, you're in dangerous territory," he says. And even if your advice is solicited, proceed with caution, because your words will live on, long after you say them.

Unlike the bonds of marriage or family, which are circumscribed by law and biology, no such thing exists for friendship, making the relationship particularly vulnerable. "We need to do know that the friends in our lives accept us and are [as] close to unconditionally loving to us as possible, or else friends are the first to go ... It's such a voluntary relationship."

3. Beware the narcissist – and your own blind spots. The person who can't feel happy for your good news, or always redirects the conversation back to himself? Those are some red flags that someone is using you for selfish reasons. "It's very hard to have a relationship with a narcissist that has mutuality and depth," Matousek says. So how do you spot the warning signs? By paying attention. "Often people are showing their hand in ways that we're not necessarily paying attention to, but the information is there," he says. "Friends very often sort of fall in love with each other" and, consequently, into the trap of idealizing someone. "You don't tell yourself the truth about what you have actually intuited or noticed from pretty early on."

[Read: How to Claim the Love of Your Life.]