Clarity. Be direct and straightforward in your argumentative writing. Directness results in clarity. Use your own language, plainly and accurately. Never use words of which you don't know the exact meaning. Avoid tortured or overstuffed sentences always. Don't waste time getting straight to the point. Don't keep your audience in suspense; suspense is for mystery novels, not for argumentative essays.
Candor. Make it your mission to be honest with your readers. Give readers something they can actually use in the real world: hard-won advice, useful facts that you've discovered, a careful description of problems, and actionable solutions to those problems. Level with your readers about important information that less courageous writers would rather not write about.
Confidence. Be both calm and firm about the rightness of your argument. Don't demand that readers agree with you; ironically, such an approach shows lack of confidence. Invite readers to agree with you and congratulate them for choosing your firm side. Acknowledge opposing points of view, but refute them immediately and resolutely. Read classic writers who argue with calm confidence, whether or not you agree with them, such as Machiavelli in The Prince, and steal their attitudes.
Control. A) Don't get distracted or go off track. Deploy the power of understatement. A strong argument has more impact when discussed matter-of-factly than when screamed or shouted. Don't quote others excessively. Always retain the first word and last word of every paragraph for yourself. B) Balance the structure of your essay. Each section of the essay should have a specific role. When it fulfills that role, move on. Avoid overly long paragraphs generally; especially avoid overly long first and last paragraphs. To prevent an overloaded beginning that merely confuses readers, avoid explaining yourself in the first paragraph. Dare your readers to be interested in the rest of your essay beyond the beginning. Let your first paragraph establish your topic and your thesis only, and move swiftly to the middle paragraphs where all your explaining should happen.
Comprehension. Whatever your topic, proactively show readers that you understand it well. Be both a helpful guide through complex issues and an informed judge when choices must be made. Cover your territory fully and give readers information that they're not likely to know. Generous sharing of useful, real-world knowledge is the fastest way to establish trust with your audience. Never forget the ultimate goal, which is to contribute your wisdom freely and help your readers sincerely.
Marc Briggs has been teaching college English courses for 25 years and has helped literally thousands of students improve their writing skills. He can help you with your writing project, too! His ghostwriting and editing services are available. No project is too large or too small. Visit http://www.fixthisessay.com or drop Marc a message at firstname.lastname@example.org. Follow him on Twitter at @marcbriggs.