WHENEVER managers hire or promote someone, they are faced with a critical choice in how they present that person within the company. They can either aggressively sell the person's talents and potential or they can take the passive route, letting the person establish a position on his own. Since circumstances vary with each new hire or promotion, a valid case could be made for either approach. But my preference is to aggressively sell the person to his peers. I was not aware a choice existed until a friend pointed out that I always did this. I had given a young but worthy executive a major bump up in responsibilities and, apparently, was singing his praises every chance I got. My friend noticed the change of tune and called me on it. ''You know, this fellow has been working for you for nine years, but I've never heard you even mention his name until he got this new promotion,'' he said. I suppose there is a logical explanation. With his new promotion, this executive and I had more contact and, consequently, I had more opportunities to observe him in action. But on reflection I think I was also selling his promotion. By advertising my elevated opinion, I could elevate other people's opinion of him as well. This, in turn, would make him more effective and would increase the chances the promotion would be a success. It's a self-fulfilling approach, which makes it all the more puzzling why so many managers ignore it. Rather than assist their newest hire or promotion, they (consciously or otherwise) resist it. This resistance manifests itself in many subtle ways. For example, we have one senior executive who insists on personally reporting all his division's activities. If I ask ''what's new?'' he will tell me about ongoing deals in five different states and three continents. I am sure he realises I know he cannot physically manage all those transactions, yet he never mentions his associates who are doing the work. The implication is that he is doing all those deals himself. I suppose he thinks crediting his subordinates will somehow diminish him in my eyes. Actually, it would make him seem bigger. The interesting thing about selling a new employee is how easy it is to do, at no expense to your ego, dignity or reputation. Here are five simple steps: Do not forget the ringing endorsement. This is the most rudimentary advice, yet people forget it. Instead of citing all the positive reasons they hired or promoted the new person in the first place (''he turned around XYZ Company's sales force in a year''), they shrug off his arrival as a non-event (''I hope he works out'' or ''it may take him some time to learn our ways''). The latter is hardly a ringing endorsement. If I were the newly hired or promoted person, I would prefer my boss did not comment at all. Urge people to get to know the new person. When a new hire or promotion does not work out, it is often because people in the company did not appreciate the significance of his arrival or what he was capable of. I am constantly cajoling our executives to meet new people in our company. If I know Joe Jones is working in an area the new person, Tom Smith, is familiar with, I will write Jones to say, ''Tom Smith knows more about this area than anyone in our company. Before you proceed any further, you should spend some time going over this with him . . .'' That kind of memo sells the new person more effectively than any compliment. Give him high-visibility assignments. As a manager, you cannot always wait for your new person to find his special niche. You sometimes have to create the niche by giving him high-profile assignments - for example, dealing with a major customer, heading up a crucial project, chairing a task force. The more serious the assignment, the more seriously your new person will be taken. Bring him to meetings. Often, the inclusion of the new person in meetings elevates their status and credibility. I will often include people in meetings even though their presence is not absolutely necessary. Doing so not only lets me introduce them to a new set of characters and contacts, but if, at some point in the meeting, I defer to them and let them demonstrate their expertise, I have enhanced their standing with everyone in the room. Do not be a roadblock. Like the executive I mentioned above, some managers are reluctant (or afraid) to expose their subordinates to the higher ranks of the company. They reserve that privilege for themselves. Of course, the opposite approach is the smarter move. It's one thing to be known as a thoroughbred executive yourself. It's even better to be known as someone who breeds and attracts other thoroughbreds, too.