San,

As one who's spent years of his life in school, one challenge I've seen that most students face – especially students these days – is being able to write well. As few people in the world are spending their time in books, and writing purely for the joy of putting pen to paper (or key to screen), the average person's vocabulary and ability to make complete, coherent sentences has reached levels that echo post-medieval times.

In addition to the previous response on "writing what you know," there are areas that you could work on polishing that relate specifically to what college instructors and professors are looking for: good grammar; clear, thought-provoking ideas and statements; and an academic writing style. The good news is that most of this you already know, but some may be buried under the dust of the modern age that we live in, which requires little use of more than a couple thousand words and a word processor.

Because you want to write papers used by sites that sell college-level essays, these skills are necessary items to work on. For grammar, I would suggest picking up a copy of Azar's "Understanding and Using English Grammar," (AKA the blue book). It's the most widely used English grammar textbook in the world, and in most grammar teachers' opinion, the grammar bible. For learning about writing styles, rewriting and some of the wonderful mechanics that the English language has to offer, one of my faves is "The Writer's Options" by Morenberg and Sommers.

Best of luck.
Brently