Dave Packard's (Founder of Hewlett Packard) 11 simple rules:

1. Think first of the other fellow. This is THE foundation — the first requisite — for getting along with others. And it is the one truly difficult accomplishment you must make. Gaining this, the rest will be "a breeze."

2. Build up the other person's sense of importance. When we make the other person seem less important, we frustrate one of his deepest urges. Allow him to feel equality or superiority, and we can easily get along with him.

3. Respect the other man's personality rights. Respect as something sacred the other fellow's right to be different from you. No two personalities are ever molded by precisely the same forces.

4. Give sincere appreciation. If we think someone has done a thing well, we should never hesitate to let him know it. WARNING: This does not mean promiscuous use of obvious flattery. Flattery with most intelligent people gets exactly the reaction it deserves — contempt for the egotistical "phony" who stoops to it.

5. Eliminate the negative. Criticism seldom does what its user intends, for it invariably causes resentment. The tiniest bit of disapproval can sometimes cause a resentment which will rankle — to your disadvantage — for years.

6. Avoid openly trying to reform people. Every man knows he is imperfect, but he doesn't want someone else trying to correct his faults. If you want to improve a person, help him to embrace a higher working goal — a standard, an ideal — and he will do his own "making over" far more effectively than you can do it for him.

7. Try to understand the other person. How would you react to similar circumstances? When you begin to see the "whys" of him you can't help but get along better with him.

8. Check first impressions. We are especially prone to dislike some people on first sight because of some vague resemblance (of which we are usually unaware) to someone else whom we have had reason to dislike.

9. Take care with the little details. Watch your smile, your tone of voice, how you use your eyes, the way you greet people, the use of nicknames and remembering faces, names and dates. Little things add polish to your skill in dealing with people.

10. Develop genuine interest in people. You cannot successfully apply the foregoing suggestions unless you have a sincere desire to like, respect and be helpful to others.

11. Keep it up. That's all — just keep it up!

Source: http://www.hp.com/retiree/history/found