Competent writing goes hand-in-hand with competent thinking. The philosopher C.D. Broad put it this way:
Broad was admonishing fellow philosophers, yet his main point applies to everyone:
If your writing is not clear, your thinking is not clear.
Indeed, whatever else you master in college, learn how to write well. No professional occupation escapes the need for clear expression. Writing well is crucial to your career. To be sure, it will take work, especially if English is your second language. Here are a few suggestions.
You needn't follow all this advice, of course. Yet some of it is likely to help. For more advice, see the following guides to writing philosophy. To be sure, there is a lot available here: Start with Lenman's "How to Write a Crap Philosophy Essay" to quickly learn what not to do; follow up with Pryor's superb "Guidelines on Writing a Philosophy Paper".