Many writers, both beginning as well as experienced writers, have trouble with the opening paragraph of a report or paper. Skip it! Write the body of the writing first, organizing it by main points or items you'd like to have accomplished, then go back to the introduction. Often something will occur to you as you write that will make a great introduction. Even if you don't get a great quote or interesting statistic from your research, when you finish you'll know exactly what your paper says, which helps in writing a clear introduction. The most important thing is to get started! Stewing for hours over how to begin wastes valuable time.
Make sure everything you say in a paragraph relates to the main point in that paragraph. If you are writing a cover letter and the first sentence in a paragraph is "I excel at working in a team," then make sure everything else in that paragraph talks about team experiences -- "I took the lead on our budget analysis team and cut administrative expenses by 20 percent," or "My team members appreciate that I can gather all the ideas presented in a meeting and distill them down into workable action items." This principle applies to writing a memo, an academic paper and any other kind of writing. Stick with one idea in each paragraph.
There are two aspects to waiting in writing. The first applies to writing a quick first draft. Just get the ideas on paper -- or the computer screen -- quickly, without stopping to worry about grammar, spelling or organization. WAIT until you have everything written, then go back and edit, fix grammar, tighten up sentences or rewrite paragraphs. Then when you have a cleaner draft, WAIT again. Put it away for a day, if you have the time. If you are under a deadline, put your writing aside for at least an hour or two, then go back to it. Read it as if you were reading it for the first time. Does it make sense? Have you assumed your reader knows information that you haven't actually put in writing? Do more editing after your "fresh" reading.
Although you will find those who advise simply beginning to write without limiting yourself to a plan, that method generally works only for those who are already comfortable with writing or who are doing creative writing. For others, effective planning is a must for effective writing. Writing either a formal outline or a simple list of the main points you want to convey will help direct and focus your communication, making it more readable and more effective. For business or school, creating a solid thesis statement, or main point for the paper, proposal or presentation will guide the tone and direction of the piece. Know your purpose for the piece of writing, and convey it clearly.
Effective, powerful writing must be clean and crisp. If it contains spelling errors or grammar errors, you will not be taken seriously. In a resume or cover letter, simple grammatical or spelling errors can be the difference between having your resume placed in the reject pile instead of the considered applicants pile. Most of us are too close to our own writing to be effective proofreaders, so asking an intelligent person to read your writing and see if you've made any errors is a wise use of time.