Look into the camera if you're doing a live-shot from a studio, talking with a reporter/anchor who is at a remote location.

• you're being interviewed by a reporter, host or producer who is there talking with you
• you're being taped while in the process of your activities

If you're the President / CEO, and you're delivering a direct message to your viewing audience, it should be delivered into the camera.  In most other cases, it's more appropriate to be looking just off camera, interview-style (someone should be sitting there, for eye-contact, and to prompt you with questions.)

In the vast majority of things you see on TV, the camera is an "eavesdropping tool".  Generally, the only people who look directly to the camera are News Anchors/Reporters, Show Hosts, Spokespersons and people talking to a network show via remote.  Otherwise, people in the course of their lives are not looking at the camera.  They're either going about their  activities, or talking to an off-camera reporter (interview style). 

The interview style is more comfortable and natural to view.  Speaking to camera calls attention to the fact that You're Giving A Speech.   Of course, for many purposes, this is exactly what you want.  But if you're the President, reflecting on company history, or a Department Head musing about the scope of the Project, or a rank-and-file employee talking candidly about the new Human Resources policies, it's more appropriate to shoot it interview-style.  Looking off camera is easier to do, and usually appears much more natural. 

When you do need to look at the camera, consider using a teleprompter, and schedule some rehearsal time with it.  At first, the tendency to "read" the teleprompter will result in obvious eye movements as you scan from line to line.  With a little practice, you can learn to "widen" your field of vision to see the whole screen, without "grabbing" each word with your eyes. 

The big advantage of a teleprompter is that the text is centered right over the camera lens.  Cue cards can be used, but since they must be held adjacent to the lens, eye contact is much more difficult.  I only recommend cue cards when they can be limited to outline items or bullet points, and used for reference.

In any case, when shooting, it is customary to run through two or three "perfect" takes, with different camera angles that are necessary for editing.