When writing blocks of conversation between two or more characters, you should use tag lines now and then to denote which person is speaking. A simple “Tom said” (or “said Tom”) will do nicely, following or preceding a line of dialog by Tom.
There are thousands of variations you can use, but if you have written distinct characters with their own speaking style, you won’t need many of them.
Examples of dialog tags:
Tom yelled, mumbled Tom, shouted Tom, Tom whispered, Tom asked, Tom demanded, etc.
“Said”, however, is the best tag line. Why? It’s invisible to the reader. “Tom said” simply denotes that a person has spoken without any unusual emphasis.
Many writers go back over their stories and decide that “said” has been overused. Then they start replacing it with synonyms with more color and excitement. This can be a mistake, because many synonyms will sound wrong to the reader and become an irritating distraction. “Said” (or “asked”, when it’s a question) is almost always best.
Publishers and editors like action tags. An action tag is a bit of action that is either followed by or preceded by some dialog.
Examples of action tags:
Tom pulled the hammer back on his .38 and pointed it at Jerry. “Take one more step…and it will be your last!”
Jerry sneered at his brother. “You think you can take me? Don’t make me laugh!”
Note that when there are only two people in a conversation, it is not necessary to have a tag line on every piece of dialog. Why? Each piece of dialog is in a separate paragraph. If the first line of dialog tells the reader who is speaking, then the next paragraph must be the other character’s line.
Sometimes you will want to break up a paragraph with a dialog tag and then continue the same character’s speech. If the character is still the same, you won’t put the continued dialog in a separate paragraph.
Example of continued dialog:
Tom pointed his pistol at Jerry. “You sniveling snake! I should never have trusted you with Mom’s money,” he said. “And if you’d steal from her, you’d steal from anyone.”
Also, a tag need not be directly attached to the speaker. In the examples shown above, it’s clear which character’s talking. As long as you have the speaker’s name within the paragraph with the dialog, your audience will figure it out.