Bear in mind that the ways you can become a writer for Saturday Night Live don't necessarily guarantee you a position as an SNL writer. The amount of back work and experience required just to secure an interview is considerable. If you aren't prepared to relocate to New York, Chicago or Los Angeles, and you aren't willing to toil in poverty with other like-minded writers and performers in clubs multiple times a week, this isn't the goal for you. If that didn't sway you, read on ...
The Groundwork: Building a Portfolio of Writing Samples
Few people are capable of dealing with the multiple rejections--or outright silences--that come with trying to secure a slot on a major television show. That hard-to-secure interview opportunity will not happen at all, however, without a portfolio of professional caliber writing samples. Make no mistake: If you're lucky enough to get in the door, you will be asked for samples of your writing, and the samples will be expected to be sharp, extremely funny and fresh (without diverting too dramatically from the show's prevalent writing style). While there's no hard and fast number regarding the number of sketches you should have ready to present, walking in with two or three pieces looks weak and not particularly productive. Think 10 or more above-average sketches, and you're getting closer to what you'll need to impress.
This step is as crucial as the first: You will need to become a writer and/or performer with an instructional comedy club that is frequented by SNL talent scouts. Specifically, the serious potential SNL writer should join Second City in Chicago or Toronto, The Groundlings in Los Angeles, or The Upright Citizens Brigade in New York. The majority of past and current SNL talent were discovered in these venues, and all of them are stocked with writers and performers who want the same thing that you do. Expect an enormous degree of competition. What you are trying to achieve by becoming a writer and/or performer with one of these groups is fourfold. First, you're looking to get direct experience as a writer by doing so in an environment where you'll be expected to produce regularly. Second, you'll discover--with a fair degree of pain and embarrassment--which comedic ideas succeed or fail before a live audience, which can't help but improve your choices and timing. Third, you'll be making connections with other writers and performers who may "plug" for you if they manage to secure a spot on SNL, or any other coveted TV show. Fourth, you'll be putting your work on display in a venue in which an SNL talent scout may very well be lurking to discover new voices. The importance of this step cannot be understated. Moving to one of these four cities may be an enormous life change, but such a move is necessary in order to be heard by the right people.
Let's assume that you--an avid student of SNL sketch comedy--have spent months or years taking writing and performing classes with Second City, The Groundlings or UCB. You've got a great portfolio of writing that has been critiqued by fellow writers and performers and by audiences who weren't afraid to let you know what they thought. Let's also assume that after all this hard work and toil, you are approached or contacted by a talent scout who wants you to drop by 30 Rockefeller Plaza in New York for an interview. Take a deep breath, accept gratefully and then, when you're out of earshot, let out a scream of joy. You've just gotten an opportunity that thousands of other writers and performers would kill to have. Remember, your portfolio of written work is your calling card. Your writing will be looked at, and--barring any off-putting negativity, ingratitude, or otherwise annoying behavior that you should not be engaging in during the interview of your lifetime--it will play a large part in deciding whether you'll be hired.
It goes without saying that if you want to write for SNL, then you're also a fan who has watched the show and is familiar with the format. While the person who's assessing your potential to write for SNL won't be looking to see if you can exactly duplicate the material of their current writers, they will be expecting you not to deviate too wildly from what the SNL audience expects. Putting a bit of a "twist" or an original personal touch on the sorts of material SNL writers have been producing that season is your best bet.