I started off by listing 10-20 potential areas that strongly interested me. These mainly included cancer-related research whether it was at the molecular, cellular, chemical, level, etc. Unfortunately, I received 20 rejection letters from all the professors 😀
I finally decided I needed to start somewhere so I pretty much looked at the available ones only. Finally, with a stroke of luck, I got one in the psychology department. I never really had much interest in it, but after speaking with the PI, I got genuinely interested in it. Plus, I decided I needed the research experience to be more competitive and felt that the basic research skills I get from this lab will suffice.
I would just try to ask as many labs as possible for a position. IMHO, where you start research does not weigh that heavily, so long as you develop the skills of a researcher.