I have always found humorous writing difficult. When I first read the Redwall series by Brian Jacques, my attempts to replicate his comic songs and characters resulted in unimpressive sludge. Even today, when I read Gillian Bronte Adam's delightfully light-hearted posts, I wish I could write like that.
So how does one write winning humor?
Given that I'm not all that successful at it, my opinion may be unhelpful, but I believe there may be some small merit in "experience by failure." With that said, here are three ways to approach writing humor.
Hold the punch line until the end.
Writers tend to overexplain the joke, so that, by the time the punch line arrives, the reader thinks, "Duh!" For example, suppose I wrote:
My sister, sick of sloppy habits, hung a sign over the laundry hamper stating, "If you don't put your clothes in the basket, they won't get washed!" On April Fool's Day, I made a small basket out of construction paper and placed it where the laundry hamper should be. When people came to put their dirty wash in the hamper, they found that the basket was too small!
The concept may be funny, but the execution stinks. Let's try this instead:
My sister, sick of sloppy habits, hung a sign over the laundry hamper, stating, "If you don't put your clothes in the basket, they won't get washed!" This gave me an idea. On April first, those with armfuls of dirty laundry discovered a lonely sock draping limply from a tiny home-made hamper. All attempts to put their clothing in the basket failed.
Instead of describing what I did, I simply described the effect.
If you notice some stupidity that you'd like to make fun of, write about it backward. Instead of saying outright, "This is ridiculous!" take the position that the situation makes perfect sense. How could anybody dare object to it? Ben Franklin, Mark Twain, and others used this technique masterfully in their own writing.
A personal example: I have long been irritated with excessive wordiness, cliches, unrealistic drama, and other plagues of literature. Attempts to simply state "This is an outrage and an offense against decent literary sensibilities!" fell flat. Out of frustration, I then wrote my post "5 Tips For Writing a Fantastic Novel," in which I instruct the aspiring writer in all the disgusting mistakes that I abhor. I think it's funny. You shall judge.
Don't try to be funny.
Whenever I break this rule (which is often), I fail. But whenever I simply report the ridiculousness of normal human behavior, people seem to resonate with it.
For example, when I wrote "Family Dynamics and Road Trips," I was quite aware that the topic of a large family stuffed into a vehicle for hours of traveling generates a certain amount of humor. I think some of the exaggerated language would have been better left out; it's annoying, as though the author keeps poking the reader and saying, "This is going to be funny. Are you laughing yet?"
The better parts of the post arrive when, rather than prepping the reader for it, I almost off-handedly remark on some silly behavior. (See the dialogue about the bathroom breaks or--my favorite--the spider.) Again, you be the judge.
Above all, be genuine. If you are a very sober person naturally, I'd recommend that you stick to serious writing, until you get an undeniable itch for a specific humorous topic.
For more on this topic, I suggest you read William Zinsser's On Writing Well, in which he devotes a whole chapter to humor writing.
Also, I realize I've only covered three possible strategies, so I open the floor to you. What strategies work well for you?