I have to say that, even though I have been playing this fantastic game for many years, I am very new to the exobiology activity. One thing that has helped me to do this activity better is definitely having used an external tool for Elite Dangerous.
I am talking about the EDCOPILOT tool which is a truly extraordinary tool. In addition to having many advanced functions and a very fun talking on-board computer, it also has a function that allows you to keep track of exobiological research.
In fact, set up properly, when you enter a system, it immediately indicates if there are planets or moons that have scannable life forms. In the dedicated tab, it even says if they have already been discovered, and if someone else has already scanned them, it provides the type and coordinates to find it.
Furthermore, after scanning, it says how far away you have to go to find another sample and, when you have reached that distance, which is the distance needed to find new samples.
If no one has scanned yet, it says that a scan is needed, and in this case, it does not provide the coordinates, but still indicates the distance after the first scan. This tool provides, if installed and set correctly, even an in-game uhd to see in which direction the coordinates are.