"Help this person"
Every time you encounter another person, think: help this person. It's not not altruistic. Nothing else can so quickly supercharge your career and improve the quality of your life. And, yes, being genuinely helpful is the most substantive “self-promotion” possible.
When you walk into Starbucks for a cup of coffee, think help this person about the barista who serves you. Instead of being frustrated that he isn't moving fast enough, see if you can make him smile. Better yet, tell him to keep the change.
When the phone rings on a busy day, don't get frustrated by the interruption. Think help this person while you answer the phone. Doing so will change your demeanor, your thought process, and the entire interaction.
If you have a subordinate who isn't pulling her weight, instead of criticizing her, every time you see her think help this person. Now, this doesn't mean let her slide, or ignore her shortcomings. It means help her either improve her skills or find a position better suited to her strengths. But don't just brush her aside; really help her.
But, wait a minute – I know what some of you are thinking. What about the people who take credit for other people's work? What about the rich and powerful who have gotten that way by crushing others? Doesn't their success prove me wrong?
Not at all. Sure, there are some people who take the exact opposite strategy. But it takes real skill and focus to succeed by being evil, and most of us just don't have the fortitude to pull it off. For those of us with a soul and a heart, the only real choice is to succeed by helping others.
By first thinking help this person, you will change the ways that others perceive you. There is no faster or more effective way to change your interactions and relationships. You will be viewed as a positive, constructive, helpful, and dependable person. People will think you are more perceptive, attentive, and understanding.
That's why this way of thinking is not altruistic; it is selfish, in the best sense of the word. The single best way to help yourself is to always be looking for ways to help other people. Sure, you'll be making the world a better place, and over the course of your life, you will help many thousands of people. But don't do it because you ought to, or because it's the "right" thing to do.