Avoid the obvious
One of the many secrets to a good joke is making the audience think. If your joke isn't working, it may be because it is not thought provoking. Of course, if you make your audience think too hard, that won't work either. But if I'm in your audience, I would rather think too hard than not at all. Avoid jokes that sounds like they written by someone in high school. My apologies to anyone from high school reading this blog. High school humor works best in high school. Your audience wants some food for thought. Make them think and you will make them laugh.