Remembering the three guidelines for distinguishing between subjects and predicate nominatives is difficult. But if you can get the guidelines down, you’ll save yourself a lot of time and errors when reading Greek.
The best way to solidify basic grammar like this is to refer back to your basic grammar notes while encountering instances in-use.
As you can see, that’s exactly what Mark Giacobbe has done in his Philippians series, with useful slides prepared throughout to help refresh you on paradigms, grammar, and syntax as you translate verse-by-verse through Philippians.
https://www.youtube.com/watch?v=ARGgIDGviDI?rel=0