Another college graduate who has written many a paper, penned many a column for the student paper, and given many a speech on the virtues of the 2A.
Here is my advice:
Don't sound crazy.
A good way to sound crazy is to talk about the gigantic threats posed to the Second Amendment by Barack Obama, the ATF, and the blue-helmeted UN stormtroopers.
When you speak about something to an audience you suspect will be hostile, you must do your homework and know the subject so well that you don't need source cards to tell you what your research says.
Assuming your audience is likely to be primarily neutral, leaning pro-gun control, or totally pro-gun control, do you really think it's the best idea to talk about the dangers of threats to the Second Amendment? To an audience that will likely applaud a lot of what you perceive as threats to the Second Amendment? Sounds like setting yourself up for failure.
Pick one specific topic that is not too overarching or ambitious. I did a literature review on research surveys that tried to measure the frequency of defensive gun use. This is not the huge "My speech is about the Second Amendment" that turns into an emotional 16-hour rant. It was a paper that identified the primary research on the subject, the conflicting research, points upon which all the research agreed, the social ramifications of the research points that were agreed upon, and ways to improve the current research.
The biggest mistake high school and college 2A supporters make in their speeches and papers is starting from a conclusion and finding evidence to support it. That is not a scientific or rational approach. It is one thing to have a hypothesis, it is another thing to have a conclusion before you do your research. Find your research, then decide what specific topic you will use.