No on likes a presenter who is constantly looking at their slides or down at a paper they're reading from. During a presentation, it's ok to briefly look at your notes, but avoid the habit of being one of those people who never looks at the crowd.
Follow the 3-1-3 Rule:
There are three sides to every room: left, center, and right. The way the 3-1-3 Rule works is: you start with the left side, pick one person, and make eye contact with them for 3 seconds. You then move to the center, pick another person, and make eye contact with them for another 3 seconds. You do the same for the right side of the room and then just repeat.
Here are the top mistakes to avoid with your eye contact:
#1: Reading directly from your slides or paper
#2: Turning your back to the audience
#3: Looking to one side or person for more than 5 seconds
#4: Only looking to one side or person
#5: Forgetting your place in the presentation due to prolonged eye contact