An interjection is usually followed by an exclamation mark to denote great emotion: pain, anger, astonishment, acute distress, joy or delight; or several of these feelings combined.
In case of several interjections, there is usually an exclamation mark after each. There may be a dash between two interjections. For example: “Hi! stop a minute, will you?”
In case of an exclamatory sentence, there is usually a comma after the interjection, and an exclamation mark (or a dash) at the end of the sentence: “Oh, Doctor Manson! I am relieved to find you in”.
If no great emotion is expressed, nor exclamation, but such feelings as pity, sorrow, annoyance, wish, pleasure, surprise, approval or disapproval (with ‘yes’ or ‘no’), a comma is put after the interjection: “Oh, that’s too bad”.
An interjection may consist of a group of words, so there is an exclamation mark at the end of the group: “Ah dear me!”
Direct address is divided by a comma or double commas from the sentence to denote its independent character and a pause. For example: “But you have just what you like, Minnie and Margery”.
Often some other punctuation mark comes after the direct address: an exclamation mark, a question mark, a dash, or a colon, in exclamatory or interrogative sentences, before introductory words, enumeration or explanation: “Be careful, children!”
Introductory words are mainly set off by a comma or double commas from the rest of the sentence to denote their syntactical independence, their detached character, lowered tone, and a pause.
Introductory words are:
1) modal words: actually, apparently, certainly, evidently, indeed, likely, maybe, naturally, perhaps, please, possibly, probably, really, truly.
2) adverbs having a modal or connective meaning: accordingly, besides, consequently, finally, firstly, fortunately (unfortunately), hence, however, happily (unhappily), luckily (unluckily), moreover, nevertheless, otherwise, rather, secondly, still, therefore, undoubtedly: “I will not be long, perhaps”.
Introductory modal words are often attached to modal verbs (usually with a suppositional meaning): ‘could possibly’, ‘may perhaps’, ‘must certainly’, ‘should probably, ‘might as well’, etc., these groups expressing double modality, that is, a greater degree of uncertainty, doubt, probability, near certainty, etc. In such cases the modal words are never set off by any punctuation mark, being part of a compound modal predicate: “He could possibly manage, before the surgery, these two calls”.
Introductory phrases, like modal words, are usually set off by a comma or double commas. In case of an appositive explanatory meaning, and a longer pause, there may be a dash, double dashes, or brackets.
Introductory phrases are:
1) prepositional: after all, as a matter of fact, at least, by the by, by the way, for example, in any case, in fact, in general, in short, no doubt, of course, on the contrary, on the one hand, on the other hand.
2) infinitival: so to say, to be frank, to begin with, to be on the safe side, to be sure, to cut a long story short, to say nothing of, to tell the truth.
3) participial: briefly speaking, frankly speaking, generally speaking, humanly speaking. For example: “But on the other hand, you must not talk to me as if I were a fool”.
Some of the above-mentioned words and phrases are used as emphatic words and phrases with a convincing meaning. They are stressed in the sentence, pronounced in a high pitch, and are, consequently, not marked off by any punctuation mark: “Of course you have only one son”.
Words of affirmation: ‘yes’, ‘certainly’, and words of negation: ‘no’, ‘certainly’ are usually separated from the sentence by a comma to denote falling tone and a pause: “Then don’t you people matter?” “Yes, they matter”.
When ‘yes’, ‘certainly’ or ‘no’ stand alone, or when a longer pause is needed, they are followed by a semicolon or by a full-stop; by an exclamation mark to denote an exclamatory meaning, or by a question mark to denote interrogation: “Yes?” said Amos sharply. It was a cry as much as a question”.
In fluent speech ‘yes’ or ‘no’ may be closely connected with direct address, so there is no punctuation mark between them: “Oh! no sir! I couldn’t do that,” she replied quickly”.