Michael at pisteuomen has done us all (especially those just learning Greek) a great service by posting his “Notes on Koine Greek.” (That is a link to his first “note.” So far, he’s published 41 notes.)
Primarily, Michael follows Dave Black’s Learn to Read New Testament Greek. When I first took a Greek class, we did not use this book as the textbook. However, it was highly recommended by others, so I purchased it as a supplement. Black’s morphological approach makes so much sense to me that I use his book whenever I teach NT Greek.