In my experience, eye contact is one of the most important but least focused-on aspects of presenting. Great eye contact includes everyone and invites them into your presentation. It engages. It shows confidence. But here is the thing—eye contact can be confusing and distracting to less-experienced speakers, so they tend to avoid it, looking over the heads of listeners, or scanning the room but not really connecting with anyone. Sadly, the lack of eye contact is perceived as inexperience or discomfort to listeners, even when that is not the case.

So how can you get better at eye contact, and to answer your question, how much eye contact is enough, or too much? Here are a few guidelines to consider.

Eye contact should feel like a connection, not a drive-by. Land on the face of the person you are connecting with. Stay there a second…or two…maybe even three. It will seem like a long time, because you are probably fueled by adrenaline, which makes you want to go faster, not slower.
Practice connecting with one person at a time, then smoothly moving on to the next person. I learned this while practicing my presentations, using chairs in the room to train myself to “land” on each one, instead of sweeping past people. You could practice it in meetings, where the stakes aren’t quite as high, and where you may feel more comfortable.
If looking directly into a listener’s eyes is very distracting, you can look at their left eyebrow. It looks just like eye contact to them, but it seems to be a little easier for new speakers. Please don’t stare at their forehead, which can look harsh, but closer to their eyes which seems softer.
Practice sending your energy outward to listeners, rather than reading them or letting their energy overwhelm you. (Experienced speakers can use eye contact to determine interest on the part of the listener, but I don’t recommend that for those with less experience; it is too distracting.) “Energy out” works fine and is easier to master.
Reach into every corner of the room with your eyes. The sides and the back often get less eye contact than the front and center. Sometimes people in the front row are so close it feels obtrusive to make eye contact with them. If that is the case, begin with those at a greater distance and then move toward the front of the room.
Find a friendly face if you can. It’s fine to focus on the one or two people you know, or those with friendly faces, but don’t get stuck there. Branch out until you are making a connection with everyone in the room, no matter what kind of energy they are sending back at you.
Don’t expect to see a friendly face. Most people wear a pretty serious face while listening. Don’t let that distract you. Just keep going, sending your energy outward, no matter what you see on their faces.

These seven tips should help you—with practice—to connect with your listeners with effective eye contact, making you a more engaged, more engaging, and confident appearing presenter. Best wishes.