Your interpersonal communication paper needs an idea to propel you forward to research. Topics for interpersonal research include verbal and nonverbal communication, differences in how the genders communicate and parent-child communication. Think about what interests you. It could be nonverbal cues that someone uses to end a conversation. The differences between how children talk to peers their own age and those older than them. You'll gain motivation to write the paper from having an idea before you.
You need trustworthy references if you want your paper to be taken seriously. Find references that are relevant to your topic in academic journals, such as the Journal of Communication, the Quarterly Journal of Communication and Communication Monographs. Your local public or college library may subscribe to these journals or provide digital access to them. Finding qualified individuals to interview works, too. Use interviews to fill in the gaps in your research, if possible. Possible interview candidates include college professors and communications professionals. Interview in person or by phone. Quote the sources accurately.
You have your topic and your research going. Out of that mass of research notes, a conclusion begins to take form within your topic. Whatever it is, that's your thesis. It must be a statement that could be argued either way. If not, it's a factual statement. If you're uncertain, ask someone knowledgeable for an opinion and help you shape a factual statement into a thesis. Once you have the rough cut of your thesis, hone it until you've clearly stated your opinion.
Proper citations are crucial for an interpersonal communications paper. Check to see if you're required to cite in Modern Language Association, or MLA, or Associated Press, or AP, style and then gather your references. If it's in MLA, you'll need a Works Cited page. If it's in AP, you'll write a References page. You can find a recent edition of the MLA handbook in most libraries. Find an AP Style guide at the Purdue Online Writing Lab.