How To Introduce Your Main Characters
(Note that if you use my system, Character Creation for the Plot-First Novelist, the last phase of the process is to create a scene for the character that could actually be the scene I describe below.)
Many novelists give little thought to how they bring their protagonist onstage for the first time. But this is very important.
It establishes in the reader's mind who this person is and what s/he is about. These things are important for your hero, your antagonist, and possibly a handful of supporting characters, as well.
Remember the opening sequence in Raiders of the Lost Ark? The bit in the jungle where Indy is going after the golden idol. By the time that series of scenes is completed, when our hero is flying away in the water plane (with a snake in his lap), we know a lot about our main character.
We know that he's an American who goes on international treasure hunts. We know he's tough, savvy, and fearless. We know he uses a whip and is fond of his fedora. We know he knows his way around ancient ruins. We also know his chief adversary. Finally, we learn about his Achilles' heel: snakes.
When that sequence is over we know our hero very well and we've learned what kind of movie this is going to be. It's a masterful introduction of the story's protagonist (and villain).
Now, you don't have to take that much page-space to introduce your hero in your novel. That sequence ran about 20 minutes, or roughly one-sixth of the movie. If you spent one-sixth of your novel introducing your protagonist it would probably be overkill.
But what I do want you to take away from this example is that the storyteller was consciously introducing his protagonist so that all the things we need to know about him are introduced.
What is your protagonist's essential characteristic? Do you know? What is it that makes him heroic and likable? (Because if the reader doesn't like your hero you're doomed before you begin.)
What would be an ideal way to show your hero doing something that reveals this essential characteristic? Think of a scene that introduces your story world, is consistent with the tone of your entire story, and shows us exactly who this character is.
That's how to introduce your protagonist.
Be sure to include in this introductory scene a hint about what's wrong with your protagonist, too. You do have something wrong or unresolved going on with him, right? Your protagonist must have a satisfying inner journey (read Tip #3), which means he must begin in a flawed condition. That flaw ought to come out at some point during the scene in which he first steps onstage.
In summary: the first time we see your protagonist we should see 1) what's likable/heroic about her, 2) what her essential characteristic is, and 3) what weakness or incompleteness your story is going to address in her inner journey.
Be conscious of how you introduce your villain, too. Come up with a scene that reveals his character and perfectly shows us what is villainous about him. What is his essential characteristic? How could you show that? And, if you want to have a more realistic villain, remember to show some redeeming quality in him in this scene, as well.
Your important supporting characters should be brought on stage in a carefully crafted way, too. Your romantic interest. Your sidekick. Etc.
These scenes all still need to advance your story, of course. You can't stop your story just to have a song and dance to bring on a new character. Every scene has to do double- or triple-duty: introducing a character, advancing the plot, and establishing a location that will be important later, for instance.
If you've taken the time to fully know your characters, then coming up with the ideal way to bring each one of them onstage ought to be a breeze for you. (Remember, my character-creation system has as its final step a monologue introducing the character you've just developed, which could be adapted for your introductory scene.)
Craft the opening scene for your main characters with all the care you'd bring if each one were a short story. Keep the example from Raiders of the Lost Ark in mind. And bring those people onstage with careful thought. You'll reap the benefits later on if you have introduced your main characters correctly.