I have never really written any form of humor stories. I enjoy comedies in theater and the movies, so on some level it seems like a natural fit. However, I always find my sci fi turns into "doom and gloom" stories. Also, it is exceedingly hard to write comedy, as what sounds funny in your head might just be boring in the mind of another.
However, I recently became aware of an anthology which specifically publishes humorous science fiction stories, Unidentified Funny Objects. I highly recommend this for light reading, and look forward to this year's edition.
I am proud to say that I recently completed a story, entitled "A Relative Hangover" for submission to this anthology. Fingers crossed!