Finding Papers

I am studying public health and writing a research paper about connected health devices. I have found many articles, but some are very hard to understand. While searching for study guidance, I came across IoT research paper assistance. Should I start with recent journal papers or review articles? How do you decide which papers are useful for a student research project? I would really appreciate simple suggestions from students who have researched IoT in healthcare. What is your best way to read a difficult academic paper?