People tend to worry about all the wrong things when they have to do a presentation. Will they remember everything they want to say? Will they be nervous and their voice start to quiver? Will the video start when they press the play button? But, the biggest worry of all should be the most important person in the room. The reaction of that one person to your presentation is probably going to be the biggest factor in whether or not your presentation will be successful at accomplishing your goal. And that's true whether there are two people or 20 in the room.
Your first step of course is to figure out who that person is. Do whatever you can in advance to learn who's going to be in attendance. Even for an external presentation to people outside of your company, it's perfectly reasonable to ask about the names and positions of those who will be attending. If there's any resistance, it's often helpful to say "we don't use canned presentations," adding something along the lines that "you want to be sure you tailor the presentation for those attending."
Once you have the names, and hopefully the role of each person, you still may not know the most important person in the room. Don't just go by the titles. The VP may be sitting in on the meeting but there may be someone with a lesser title who's the key decision-maker. Figuring that out is usually easier with an internal audience but even when presenting to an outside party, if you have a good relationship with your contact, do be afraid to ask, "Who's the key person we need to convince?"
Once you think you've identified the most important person in the room (TMIPITR), try to learn everything you can about them. Fortunately, sites like Google and LinkedIn have made that a relatively easy task that can often be accomplished in a matter of minutes rather than requiring the hours of research previously required. Armed with this knowledge, you might make reference to a shared collegiate experience ("Big Ten football certainly was intense!") or mention your last visit to the city where they live. Creating common ground on a personal level at the onset can help connect and set a positive tone for the rest of the meeting.
During the presentation, try to be very aware of the reactions of TMIPITR. Is she nodding in agreement? Smiling? Those visual cues are very likely going to be noticed by the others in the audience and help your cause. Is she frowning? Checking the messages on her mobile? In that case, try to get her reengaged by acknowledging something she has done in the past. (Avoid asking a direct question since you might end up embarrassing her and making the situation worse.)
Don't focus all of your attention on that person. You don't want to be that obvious and it could seem patronizing; be sure to engage everyone in the room.
When it's time for Q&A, be prepared: the first comment often sets the tone for the rest of the follow-up and Q&A session. If that first response is hostile and argumentative, you're likely to remain on the defensive. If you think TMIPITR is leaning toward a favorable response, getting their opinion out there first can be a big help. On the other hand, a dismissive comment could be disastrous.
Watch the body language and reactions during the presentation. If TMIPITR is unlikely to be your cheerleader, was there someone else in the room who seemed like they might be? That's the person you want to get the first comment out after you finish.
The reality is that people are very often swayed by their colleagues' opinions. Even movie reviewers don't like being the outlier; the one who hated the movie everyone else loved. And in business, TMIPITR is often going to have an outsized influence on everyone else's opinion. Often, people find out afterwards who was the most important person in the room. Find out before and you'll increase your odds for success.