Psst… I have a secret your old high school English teacher didn’t want you to know. It’s okay to begin with “And” or “But.”
There’s a good reason your English teachers didn’t want you starting sentences with a conjunction. Developing strong writing skills is all about learning clarity and precision, and academic writing especially requires a certain language formality—the same formality that requires the proper usage of who vs. whom and semicolons. When students grow up and write professional correspondences, being in the habit of starting sentences in ways other than a conjunction will be a benefit to them.
But, of course, avoiding conjunctions at the start of sentences isn’t a hard rule. If you’re writing for a professional audience, an academic audience, or perhaps your grandmother, don’t do it. However, in other cases, a well-placed conjunction at the start of a sentence can be an effective attention grabber.
And it’s a bit more savvy than jazz hands or spirit fingers (oh, you know you get the Bring It On reference; don’t deny it).
Starting sentences with a conjunction is an art of moderation. If you do it too often, your writing comes off as sloppy and/or unorganized. If you do it infrequently, though, that “and,” “or,” or “but” can pack a mean literary punch.
There are a lot of hard rules we were once taught that don’t always apply. (For example, a well-placed sentence fragment is a personal favorite of mine. Really.) The difference is knowing the rules before you can break them. My argument is that, with moderation, you can absolutely use conjunctions at the start of a sentence.
Go for it, you grammar-rebel. And have fun.