Collect samples of your written work and organize them into a writing portfolio. A portfolio is a collection of work intended to demonstrate your abilities to someone else. Your portfolio should include samples of academic writing similar to that which you are expected to produce in your college program. If you are an arts student, include essays and research papers. If you are a science student, include research reports. If you are a student in a career-oriented program, include project reports and/or experience summaries.
Make an inventory of writing rules for college writing. If you do not have any resources at your disposal, contact your college's writing center for help with this. Some basic principles to keep in mind include consistency, logic, clarity, and convention. Consistency encompasses tense consistency, parallel structure, noun-modifier agreement, and subject-verb agreement. Logic includes coordination, subordination, comparison, and word ordering. Clarity includes specificity, succinctness, and accuracy. Conventions include rules on sentence fragments, idioms, and double negatives. See resources for more on this subject.
Review your work for grammatical errors. Read over samples from your writing portfolio and note any corrections that your professors made. Try to find a pattern of mistakes in your writing. Many people who are generally proficient at writing have one or two mistakes they consistently make. For example, some people are weak when it comes to forms of the word "you" and frequently make mistakes when using the words "your" and "you're."
Review your work for ways to improve it stylistically. Academic writing should be organized and coherent. A good paper should have an introduction, a thesis statement, a number of body paragraphs, and a conclusion. Each paragraph should deal with a discrete component of the main argument, generally a point of logic or evidence. Look over your sentences to make sure that they demonstrate parallel structure and stylistic unity. Focus on eliminating wordiness and incoherence.
Use a dictionary and a thesaurus to check your choice of words. When writing academic papers, many students make the mistake of thinking that large words are preferable to small words. Nothing could be further from the truth. In college writing, succinctness is highly valued. Although college professors expect you to use subject-specific jargon, they do not usually want to see flowery diction in places where it is inappropriate. Use your thesaurus to find more succinct alternatives to "bulky" sections of text.
Practice assembling resources to create an informed argument. Find a college-level essay topic in a field you are comfortable with, and begin doing research on that topic. Look up books, scholarly articles, and encyclopedia entries relating to the topic. Read extensively, and use what you read to distinguish between your opinions and documented facts. In college writing, you must present informed arguments, and in order to present an informed argument, you must be able to separate opinion from fact. If you do not have any paper topics on hand, check bestessaytopics.com for suggestions.
Write a "practice" essay, taking into account all the areas for improvement you have noticed. Use your research findings to craft an argument that is informed rather than speculative. Look over the comments you received from your professors on past work, as well as notes you made when you were reviewing your own work. Refer to these whenever you are unsure of what to do.