Choose your partner wisely. We're attracted to people for all kinds of reasons. Evaluate a potential partner as you would a friend: look at their character, personality, values, generosity of spirit, the relationship between their words and actions and their relationship with others people and how they treat them.
Know your needs and speak up for them. A good relationship isn't a guessing game. Many people are afraid to state their needs and as a result they camouflage them. The result of not being honest is disappointment at not getting what you want and anger towards your partner for not having met your needs. Closeness can't occur without honesty.
Respect. Mutual respect is essential, inside and outside a good relationship.
Know how to manage differences. Learn how to handle negative feelings that are the unavoidable byproduct of the differences between two people. Stonewalling or avoiding conflict isn't managing them. Arguments can be a healthy part of a relationship as long as you and your partner understand how to communicate and work out issues in a calm manner.
Communicate. If you don't understand or like something your partner is doing, ask about it and why they're doing it. Talk and discuss, don't just assume.
Solve problems as they arise. Don't let resentments simmer. Most of what goes wrong in a relationship can be traced to hurt feelings, leading partners to become defensive against one another and to become strangers, or even enemies.
Learn to negotiate and cooperate. People's needs are fluid and change over time. Life's demands change too, so good relationships are negotiated and renegotiated all the time. Sharing responsibilities is important too; relationships only work when they are a two way street with equal give and take.
Listen. Truly listen to your partner's concerns and complaints without making judgement. Much of the time having someone to listen is all we need to solve problems; it opens doors to confiding worries or fears, which is the root of real trust.
Be empathetic. Empathy is crucial for a solid long-lasting relationship. It's important to look at things from your partner's perspective as well as your own.
Apologise. Anyone can make a mistake. Being able to say sorry is crucial. Attempts to apologise can be clumsy or funny, even sarcastic, but the willingness to make up after an argument is central to every relationship.
Forgiveness. The flip side of an apology is forgiveness, so if your partner apologises, don't reject it. Accept it and put the fight behind you and don't bring it up in future disagreements.
Maintain some independence. Depending on your partner for all of your needs is an invitation to unhappiness for both partners.
Keep things new. Enrich your relationship by bringing new interests into it from outside. The more passions in life that you have and share, the richer your relationship will be.