[Lazy Meatball]

i helped my friend out on his brief amateur open-mic standup career for a little while. Everyone telling you how hard it is and that you're not as funny as you think you are are probably right, but that shouldn't discourage you from at least give it a shot. Like you said, you're only trying to have a little fun so why not.

I hope you are comfortable with public speaking and improvisation. I say practice talking up strangers at parties, not running material, but just getting comfortable telling BS and not being embrassed when called out on it.
When writing jokes, get to the punchline, quick. Edit out everything out of the set up that is not essential to the punchline.
Also, find a loyal group of friends to come see you at open-mics. While eventually you'll have to be comfortable in front of complete strangers, it doesn't hurt to have a few people who get your sense of humor, and if they buy alot of drinks club owners will be happy to have you back.