NEVER USE AN ADVERB TO MODIFY THE VERB ‘SAID’
There is a definitely a lot of truth to this rule. Do we really need to write ‘Jane said excitedly’ or should Jane’s words carry across the realisation that she is excited? Is it necessary to put in terms like ‘gravely’ or ‘loudly’ or ‘boorishly’ to communicate how the character is speaking?
These things are often not required. I have tried to avoid them as much as possible in my writing, but there have been times when I’ve felt it works better with them. Perhaps that’s because I am still inexperienced. Whatever the reason, I do think they should be kept to a minimum. Words that end in ‘ly’ can get tedious anyway.
However, it does have to be remembered that this is the way a lot of people talk. I’ve heard people use these kinds of descriptions in general conversation. So if you’re trying to relate to a particular age group, or your trying to imbibe your writing with the identity of the character you are writing about, is it acceptable to use these kinds of terms? Perhaps, as with everything, use in moderation is best.