It doesn’t help if you have to code shift from a slang-laden, adjectival, adverbial, style to a more formal. more precise, concise style. Tone isn’t particularly important in academic writing. The best way to start is to write and then go back and revise specifically for tone. The more reading you can do in solid nonfiction, the easier you’ll slip into writing it.
I told my students don’t get hung up trying to get everything right the first time. Get the ideas on paper as briskly and concisely as you can. Revision comes later. By the way, I know some teachers say that students should rewrite their papers. The best writers I know seldom consider a second draft or a rewrite. They leave time to revise and they can be tough on themselves.