Banana Joe has a decent idea, Kuba Bill. Take a look at the
FREE FAA manuals to see if the areas of knowledge even interest you. You may look at them and be bored absolutely senseless. But the info in these manuals is base-level. If you can't see yourself slogging through it, later licenses won't be any more appealing.
https://www.faa.gov/regulations_poli...aviation/phak/
https://www.faa.gov/regulations_poli...lane_handbook/