1. When ridiculing/bashing, don't just ridicule or bash. That's just being mean. You have to imply how it's funny, and then have some empathy. Try to get something clever out of it. Actually, ridiculing yourself makes people like you more, and the more they like you the more they find you funny. But don't ridicule yourself to the point that it just seems like you have low esteem, because no one likes a whiner.
2. When telling an anecdote, don't go on and on detailing small things that don't matter. Say the bare minimum without taking away from the joke, and be succinct with your words. No backtracking, no stumbling your words, no tangent or ramble. Just say the joke and make your words glide smoothly.
3. If you're pretending to be annoyed and angry, don't actually be annoyed or angry. Break out of the act at points, allow some breathing space.
4. Ignore the first three points, because they're all pretty stupid anyway. If you see someone being absolutely stupid, you can say that: "hah! I saw this stupid lady cross the road but she left her kid on the other side and he was crying and in order to get back to the other side she had to, like, there was this traffic light thing you see? And first she had to...."
Yeah by then no one is listening to you anymore.