Hi, Toni, I'm also applying to graduate schools and am not a PI, but I will tell you what has worked for me. I emailed a lot of professors, and many did not reply. However, some did and seem very serious about having me in their labs. I ended up with four very good prospects after emailing at least 15 PIs. You just have to keep emailing and not be too hard on yourself when you don't get a reply. The professors who do not email back may simply not need a student for this term.
Rather than being specific, I gave several general interest topics that I would like to pursue in my emails, tailored to the professors' research interests. I am open to studying several different areas, but I only mentioned the areas in each email that pertained to that particular professor's research interests. Like I said, I am in the same position that you are in, but I wanted to try and help by offering the best advice I have. I wish you all the best in your graduate school search, and I hope you have a wonderful rest of the day! -- Heiler
