Is there a formulaic method to get phrasal verbs right without even having read them all? To clarify, if I know the meaning of a common verb, say GET, how can I, without committing to memory the innumerable phrasal verbs, know the exact meaning of any particular phrasal verb of the word ? Or is there no such heuristic and I simply have to study them all to be able to use them?
Unfortunately, no, there isn’t, at least in a useful way.
The most important words to learn are the oldest, shortest and most often used, which means they have also evolved the most over time and may have multiple meanings, irregular (often vestigial) forms, strange idioms, etc.
Newer, longer words tend to be more regular simply due to less use, but that also means they are individually less useful to know.
No, there is absolutely not a formulaic way to do this, any more than there is a formulaic way to know how to spell an English word you have heard but not seen written.
As with spelling, there are some patterns, which can help you learn, and may sometimes let you guess the answer; but your guesses will sometimes be wrong.