“Said” is a useful word—it tells readers who’s speaking and when. It’s also an over-used word—it tells readers who’s speaking again … and again … and again.
Used too often, “said”—a dialogue tag—becomes tedious and contributes to glazed-eyes syndrome, which is usually preceded by the mouth opening into a large “O” shape. The storyline/plot becomes flat and can discourage readers from continuing. An overabundance of these puppies in your book will serve to distract and/or detract. 
Yes, now and again—particularly with lengthy dialogue/conversations—we should be reminded who’s speaking, but not with every piece of dialogue. There’s no need to constantly advise readers that a character said something; this should be obvious via the conversation and/or action.
Dialogue / dialogue tags serve these purposes:
♦ distinguish who’s speaking ♦ communicate who we should identify with (feel sympathy for, be angry with) ♦ keep us from becoming bewildered (who’s talking, what’s being said) ♦ break up lengthy dialogue ♦ add friction / create ease / advance a scene ♦ sound natural, and ♦ offer new or fresh information (not repeat what we already know).
While the following identifies the speakers and tells us what’s transpiring, is it interesting? Does it make us want to read further?
“Jim’s picked up dinner,” Leslie said.
“He usually does on Thursdays,” I said. “I’d have been surprised if he hadn’t.”
“Maybe we should help him set the table,” said she, looking toward the kitchen.
“Nawww, he doesn’t like having people get in his way,” I said.
I don’t know about you, but I feel a yawn coming on. Why don’t we aim for something a tad more descriptive and active?
“Jim’s picked up dinner,” Leslie advised softly, peering into the kitchen.
“He usually does on Thursdays,” I reminded her. “I’d be surprised if he hadn’t.”
“Maybe we should help him set the table,” she suggested, waving me over.
“Nawww.” I shook my head. “He doesn’t like people getting in his way.”
A teensy-weensy better. We have a little action. Let’s give it more oomph; we can remove some of the descriptive prose/action or add extra wording to paint a more vivid picture.
“Jim’s picked up dinner.” Leslie hopped to her slippered feet and padded to the kitchen door. Quietly, she peered inside. “Oooh, we’re having Thai.”
“He usually does take-out on Thursdays,” I reminded her and, stepping up behind, gazed over her knobby shoulder. Our youngest brother was whistling happily as he unpacked two huge bags. I was reminded of the days when my sister and I took over for our ailing mother; given the circumstances, we’d done a pretty decent job of raising the kid.
Her high brow furrowed like a plowed field. “Should we help?”
“He doesn’t like people getting in his way.” I chuckled, recalling Jeremy’s petulant pouts when things didn’t go his way. “Let him do his thing.”
Add visuals (details, descriptions) wisely—more in moderation than in excess. Too much of anything can be overwhelming, just as too little can prove underwhelming; both approaches lead to huh-duh moments. Think: balance.
Utilize adjectives and adverbs resourcefully. When strategically added to dialogue tags, they’ll not only provide specific information about the speaker or situation, they’ll make a story come alive.
Consider the different deliveries (and interpretations) of these:
“Challenges are part of life,” Jake said.
“Challenges are part of life,” Jake said flatly.
Jake sighed and smiled ruefully. “Challenges are part of life.”
“Challenges are part of life,” Jake spat, flinging the phone across the room.
“Challenges are …” Jake struggled to find the right words and sighed loudly when he couldn’t. With a limp shrug, he murmured, “A part of life.”
. . . “Feel free to use ‘said’, but use it prudently,” the blogger said. <wink>
The Writer's Grab-Bag 