When writing dialogue, it can feel like you are writing an endless stream of names, pronouns, and dialogue tags. It can be a delicate balance between avoiding repetition and making sure the readers know who is talking. One popular solution recommends changing up the verbs in your dialogue tags to things like "whispered," "cried," "shouted," etc. Technically this does remove the repetition of "said," but it is not a solution that works well on a large scale.
Dramatic and exciting dialogue tags can work well in middle grade books, but in young adult or adult novels they should be used sparingly.
"Said" is like punctuation. When placed correctly, it becomes almost invisible to the reader, simply a marker to be used to indicate the speaker of the surrounding words.
"Asked" would then be your question mark. Fairly common, but not always the right choice. It only works when there is a real question involved.
Other verbs should be viewed as exclamation points. They can be the right choice, but using too many is distracting, loses its effect, and can come across as juvenile.
When writing your first draft, stick with "said" as often as possible. Writing is slower than reading and many writers flesh out the dialogue first and then add descriptions later, so there is a good chance your first draft will feel much more repetitive to you than the scene will to readers later.
If, during a later revision stage, you still notice a real overabundance of the word "said," try using beats, moving the dialogue tag to the middle of the paragraph, or removing the dialogue tag entirely. Most conversations can be fixed with these methods.
If your scene is still feeling repetitive after using these tricks (and taking a good long break from the scene to reset your perception), then you can start considering other verbs. When choosing to use a verb other than "said," make sure to use a verb that adds to the flavor and tone of the dialogue. A speaker can shout or whine, but most characters shouldn't usually proclaim their dialogue. Choose your verbs in order to clarify the situation, the tone, the overall mood of the scene, and add depth to the characters. Don't choose verbs to be unusual or unexpected. You want them to add to your scene, not disrupt or distract from it.
Happy writing!