Never lie.

Even if you sound rude, even if you think your friend will hate you or just think it is inconvenient, always tell the truth. In time, the other person will find this very valuable.

If you think about something you think you should say, just say it.

Of course, you don’t have to make unnecessary comments that are pointless, but if it’s a valid comment/reason/compliment/information, your friend will like it if you feel comfortable enough to tell.

Trust.

If you consider the person your best friend, trust that person above anything or anyone. Even if you think “I’m stupid, it’s a lie…”, trust. Of course you can be betrayed, but the more you trust the person, the badder he/she will feel about lying to you, which means less chance of betraying.

Effort.

Understand that, as a best friendship, you need to make great efforts and sacrifices. Sometimes you’ll wish you didn’t do it, but it’s part of the thing. Remember this is a mirror, if you try very hard, the other person will do it as well.

Give up the fight.

Don’t argue over things that are pointless. You’ve took much time to build the friendship, and don’t need to destroy it in seconds. Although this doesn’t work in every fights, it’s useful in many of them. Simply let the other person win. If you do this, the person is likely to surrender as well, and you’ll both install peace.

 Don’t hide your feelings.

No one knows if you’ll die tomorrow (bad thought, but true) and things like “I adore you” and “You mean the World to me” can remain under your deepest feelings, and you’d die without letting your best friend know how important you are. Dedicate, and leave out all the rest.

(and The Fundamental Law Of The Best-Friendship) – If the person is your true best friend, the relationship is a mirror.

If you don’t know what to do, imagine what you would like that person to do. When try to guess the person’s thoughts, act reflexe and check your own thoughts in the same situation. This is the law you should lead the relationship by, and in weak friendships (not the Best Friend) it is likely to fail.