ALT-1 How to become a Comedian as a Profession
Write. Write down every thought, every observation, every thing that comes from your mind freely, and then every thing that you have to squeeze out of it until you don't even know what a parasquatter means. Write every day, every chance you get, and buy a recorder, and read that stuff into it, and play it back and write new thoughts that emerge from this process, then write some more. Play your recordings back, every new idea, every joke you can think of, and then write some more. Write.
Organize your thoughts. You will come up with a multitude of premises. Premises are not jokes, they are a foundation of jokes, but you need to flesh all your ideas out and organize them, catagorize them, and mold them into perfectly crafted material. This takes time. If you force it too much, you may over work a great premise and kill the joke. Be patient, be kind to yourself, trust your judgement and listen to people who know what they are talking about. If someone is successful at what you are attempting to do or become, pay attention to them, they are there for a reason.
Be bold, find an open mic night and sign up and try your material out. Record your set on your recorder and play it back. Make notes of where the laughs happen, for how long and things you think you can do to improve your set. Did I mention there would be a lot of writing involved?
Keep at it. You may bomb your first time out, if you give up after that, you are losing the professional aspect of this business. It takes practice and hands on work to become a professional and giving up because you didn't get the laughs you felt you deserved makes you an amateur.
In time, you will find that you have more writing than you know what to do with. That's good! Most of what you have written is probably crap anyway. You'll learn what to keep and what to lose by performing the material. A pro once told me, "deliver the material, the laughs will come." It didn't seem like good advice at the time, but the truth is, if you don't work your material out, you don't learn anything.
Be original. You will be tempted to be the fartmaster joke teller or find that you can impersonate some great comic and know their stuff word for word. DON'T. If you do that as a bit, fine, keep it brief, funny and move on, NOBODY LIKES A THIEF OR A HACK! Trust me. Just because Carlos Mencia is famous, doesn't mean he is respected or well liked in the comedy community. Everyone knows he is a thief and it is a mystery of the universe as to why he is still working and hasn't been beaten to death with a rake by digruntled comics from everywhere.
Work every chance you get. Every gig you get offered, take it, the work will not always be there. Work as much as you can, record your sets all the time and listen to them and make notes, write tag lines and new jokes and plan on the next set you will be performing. Hell gigs are an absolute necessity! The more adverse crowds you can make laugh, the better a comic you will be. I've seen a handful of headliners that absolutely CANNOT perform for less than ten people without pooping themselves, and believe me, they lose respect by cancelling a gig because they think they are too big to perform for small crowds. Do it. Make yourself the best comic you can be by performing for your audience. If they paid to see you and you bail on them because you are a chicken turd, you are essentially worthless. (THIS DOES NOT APPLY TO HYPNOTISTS WHO RELY ON AUDIENCE PARTICIPATION OR IMPROV PLAYERS-though I recommend you do your best anyway).
Keep at it, and keep your expectations low. You are not going to score a Letterman spot, unless you are really lucky or someone with money is backing you in your first month. You may never get that spot. Focus on the next gig, and have fun while you are doing it. If it becomes a job or your focus is fame or money, you've already lost and will be greatly disappointed. You have to love entertaining people. There will come a time that it becomes for you, but you are putting on a show, make that your number one priority. IF you are any good, the money and the fame will follow.
Keep a positive attitude and be kind to everyone you work with. You never know who can do what for you or to you in this business. Being a cocky jerk can cost you work down the road. Your reputation will travel more than you will. If you put out a good vibe amongst your fellow comics, that word will spread and you may get gigs from people you never met because of someone you did meet and were kind to. There are plenty of jerk comics out there, avoid following that path.
Travel. Get out of your home town. Do open mic nights everywhere you can. You may find you aren't as funny in Louisville Kentucky as you are in Denver Colorado, or the other way around. Take notes, find out what people in other towns are laughing at. Learn a little about the town before you do your set. Relate-ability is key to your audience. IF you plug into them, they are more apt to pay attention to you.
Will these things alone make you a pro? They did me. Now, I am headlining my own show in Las Vegas Nevada. It took about a decade to get to that point, but I also maintained a series of jobs and relationships. IF you can devote all your attention to your career, you may find you are headlining in less time.
Good luck.