A common beginning writer’s fault is to use stilted dialog, tagged with many “he said” or she said” attributions.   The vibrancy of an immediate moment can be emphasized by using dialog in the following fashion (avoiding the "He said", "I said", and "She said" words):

            My mother turned from the window to look at me.  "He's your brother, Sylvia.  He wants to help...let him."

            She was right, of course, but I still felt uncertain. "It's only that I want to make it on my own."

As is shown, using an introduction or transition sentence just before the actual quotation can both convey who the speaker is as well as some sense of the speaker's emotional feelings or physical setting.  These little sentences add flavor to the story and make it come alive to the reader.