Depends what you're approaching them for....there's some good threads on the board about the difference between NCM's and Officers for a start...
Think of your NCM as the "lead hand" in the warehouse, who's been there for 20 years. As an officer cadet, you'll be the college puke manager. How would you approach the lead hand?
Do your research, try not to annoy him by asking dumbass questions and don't get in his way. Ask specific questions which get direct answers, or simply ask for his help when he isn't busy. People are still people, and the whole "more flies with honey" approach is still valid.
As an Officer, you will receive instruction in leadership, and you will learn techniques for approaching, handling and dealing with people. In the interim, you might try reading some things by a guy named Wavell.
There is also a recommended CF reading list on the Regimental Rogue's site, which could give you a leg up on some of these things. Starship Troopers springs to mind offhand.
Officer Cadets are really the lowest form of life in the army. They are Officers by presumption, not by experience or training. They can't do simple miltary tasks, and they haven't been trained to lead yet...in the eyes of their future subordinates, they are useless. In the eyes of other officers, they are untrained, and therefore, largely useless. This doesn't mean anything...it's a condemnation of your state as a new, untrained person, not your value as a human being. Once you become a seasoned officer, you will either retain or lose the status of "useless" in the eyes of your subordinates, depending on how well you learn your lessons first time around...
Ask questions. Learn from the people who came before you. Do not offer your opinions or ideas until you are damn sure that they are of some use--because starting out, there is a lot you don't know, and there is a lot you have yet to learn. Be the grey man...fit in, and learn.