Should I use a comma before “and” or “or”?
Is it appropriate and/or advisable to use a comma before 'and' in some situations?
Yes, it can be appropriate and advisable. Some examples from Carey's "Mind the Stop" are helpful (p49 in the 1980 reprint of the Penguin edition):
The first shows a case where the comma before and is very necessary, and the second shows a case where the absence of the comma leads you astray on first reading the sentence.
Commas before and are useful in cases where there are two independent clauses that require linkage; for example: