Well, this will force you be sure about the various clefs!
I'm glad you are reading the Fux counterpoint book. Its an excellent study.
As you may have noticed from studying the Fux, the study of counterpoint is segmented into chapters or "Species". And so, as expected we will start with 1st Species counterpoint.
As you may already know, counterpoint is all about "note against note" creating melody and harmony at the same time. Its like a orchestrating or creating a world of consonances and dissonances. Kind of like a world of balance and counter-balance.
1)In the study of 1st Species we deal ONLY WITH CONSONANCES.
Our harmonic consonances will be the 3rd, 5th, 6th, octave and unison.
The unison, octave and 5th are called "perfect consonaces".
The 3rd and 6th are called "imperfect"
All the other intervals like the 2nd, 4th, 7th are dissonances. But we won't be dealing with them in the 1st Species.
Here are the voice-leading rules when dealing with consonaces.
1) A perfect consonaced may ONLY be approached by contrary or oblique motion.
2) Imperfect intervals may be approached by direct, contrary or oblique.
Makes sense so far?