Humor Me: Putting Laughter in Writing

Okay, so that is a really bad pun. I couldn't think of a more interesting title for this overdue post, however, and I'm sort of rushing to write this and post it. So please, forgive my punniness.
I thought that I'd talk a little bit about writing humor today. Not comedy - I haven't the faintest idea how to do that - but just little specks of humor throughout a story to lighten up the mood. I've noticed three ways authors get me laughing: through the narration/writing style, through character dialogue, and through character motive and action.

A few books that fit into the first category are Alcatraz Versus the Evil Librarians and the Percy Jackson series. They're both written (mostly - I think Alcatraz had a little second person in there too) from a first person point of view, which makes the main character the narrator. This offers plenty of opportunities for the MC's sense of humor to leak into odd places in the book. And that is the key - it is the narrator who is being funny, not the author. These books have a very light feel to them, despite the monster-battles and super-powers. Look at the following quotes from those books:

"People can do great things. However, there are some things they just CAN'T do. I, for instance, have not been able to transform myself into a Popsicle, despite years of effort." - from Alcatraz Versus the Evil Librarians by Brandon Sanderson

 "Hades raised an eyebrow. When he sat forward in his throne, shadowy faces appeared in the folds of his black robes, faces of torment, as if the garment was stitched of trapped souls from the Fields of Punishment, trying to get out. The ADHD part of me wondered, off-task, whether the rest of his clothes were made the same way. What horrible things would you have to do in your life to get woven into Hades' underwear?" - from The Lightning Thief by Rick Riordan

Essentially these are funny because the narrators are funny. Percy is ADHD (which leads to him making strange, out-of-place observations), and Alcatraz has a sort of dry humor. And because they are narrating, their humor colors the entirety of their books.
Also, another observation on the above quotes - notice how both begin with a sense of seriousness? With the first, you're expecting some profound philosophical statement about how people can do anything if they put their minds to it. Then you get Alcatraz saying he's tried turning himself into a Popsicle. In the second we get the increasing sense that Hades is a bad dude. We're dealing with trapped souls and the god of the underworld. Then Percy starts reflecting on the guy's underwear. Both of these are total changes of mood. Serious to funny. The sudden change catches readers off guard and, with any luck, makes them laugh.

Next up is humor through character dialogue. This is pretty much a no-brainer, but I've come to a perhaps not-so-startling conclusion in relation to it. There's no sense in trying to be funny. You can't force it, so if it doesn't "just happen" then don't bother. You know why? Because, like with the narration point above, it shouldn't be you who is funny. It should be the characters. If you want some light, happy, laughter-provoking moments then make certain that your characters have senses of humor! Whether it is sarcasm, pranks, ridiculousness - it doesn't matter.
Quite a few books have this style of humor. It's easy to fit into any point of view (remember, the writing style/narration one only really works when you've got a narrator and are therefore using first or second person). A few books stand out to me, though, so here are another couple quotes that I dug up on Goodreads:

"'Harry!' said Fred, elbowing Percy out of the way and bowing deeply. 'Simply splendid to see you old boy-'
'Marvelous,' said George, pushing Fred aside and seizing Harry's hand in turn. 'Absolutely spiffing.'
Percy scowled.
'That's enough, now,' said Mrs. Weasley.
'Mum!' said Fred as though he'd only just spotted her and seizing her hand too. 'How really corking to see you-'" - from Harry Potter and the Prisoner of Azkaban by J. K. Rowling

"'You see the dilemma?' Ham asked.
'I see an idiot,' Breeze mumbled." - from Mistborn: The Final Empire by Brandon Sanderson

"'So long as you don't bleed in the shape of wing joints, you should pass for human. Oh, and don't let anyone pick you up. They'll know you're not right as soon they feel how light you are.'
'I'll be sure not to let anyone but you carry me in her arms.' - from Angelfall by Susan Ee 

 "'Any sign of them yet?' he asked.
Will looked at him. 'Yes,' he said. 'A party of fifty Scotti came through just twenty minutes ago.'
'Really?' Horace looked startled. He wasn't fully awake yet.
Will rolled his eyes to heaven. 'Oh my word yes,' he said. 'They were riding on oxen and playing bagpipes and drums. Of course not,' he went on. 'If they had come past, I would have woken you - if only to stop your snoring'
'I don't snore,' Horace said, with dignity.
Will raised his eyebrows. 'Is that so?' he said. 'Then in that case, you'd better chase out that colony of walruses who are in the tent with you...of course you snore.'" - from The Siege of Macindaw by John Flanagan

A limitation to using this kind of humor is that your characters have to be in the right mood to joke, and they have to have time to talk. You can't use this when your character is alone, or grumpy, or breathlessly sprinting for his life. It wouldn't make sense and it would feel forced.

And then of course there is simple character action. This is very similar to the dialogue in that it is driven by individual characters who aren't narrating. It is unlike it, though, in that the humor doesn't come from anything spoken but more from what the character's motives are for what they're doing. Take the following quote.

"Halt regarded him. He loved Horace like a younger brother. Even like a second son, after Will. He admired his skill with a sword and his courage in battle. But sometimes, just sometimes, he felt an overwhelming desire to ram the young warrior's head against a convenient tree.
'You have no sense of drama or symbolism, do you?' he asked.
'Huh?' replied Horace, not quite understanding. Halt looked around for a convenient tree. Luckily for Horace, there were none in sight." - from Halt's Peril by John Flanagan 

That was the only example I could find for this one. But notice that the humor comes from Halt's simple desire to bash Horace's head on a tree, not from him saying that he'd like to bash Horace's head on a tree. The word "convenient" just makes it better. :D

What are your observations on writing humor? Have you had any success writing it yourself? Share a quote!