College writing has different requirements that high school writing. In college, you are expected to perform at a much higher level, yet most students find themselves unprepared for the rigors of college writing.
Here are a few helpful tips to get you up to snuff in your college writing courses.
Know English sentence structure. You think this would be obvious, but it isn't always. Not many students know how to form well-structured English sentences, so you should know how to do this.
Go to the writing center. These exist for a reason. Take advantage of them.