Written language, dating back to Cuneiform (3000 BC), is a means of expressing individual thoughts and ideas to society. Interestingly, language has developed to a point where we have double entendres, tones (angry, serious, boastful), and various modes (persuasive, informative). In our constantly changing society, becoming a good writer is important. The ability to spread a message quickly and succinctly has become an important tool in rights movements, college and job applications and laws.
Stand out
In order to stand out from the crowd, you must have control of the basics. You can't be making there, their, and they're errors. You should know where to place punctuation marks and stay away from run-on sentences. This doesn't mean you have to memorize every grammar rule, although it can't hurt if you do.
Reread to check for clarity
If you're writing an essay, or even a paragraph, be sure to reread it. It's better if you can put down whatever you are writing for a few hours before re-reading so that you have a fresh pair of eyes. Make sure your first sentence connects to your last sentence, like a hamburger bun (Shout out to my 6th grade English teacher!). Look out for redundant phrases. Often times, writers tend to reword the sentences they've already written. If your main point and supporting details are clear, there is no reason to repeat what's already been said.
Add flair
Whenever possible, try to substitute mundane sentences with creative sensory details. If you can replace "John's wavy brown hair" with "John's ridiculous chocolate mousse atop his head," do it. Sensory details add tone and keep the reader engaged. Try to stay away from cliches such as "Amelia's eyes sparkled" because cliches are dull and boring.
Use these general tips to help improve your writing. As with everything, practice is important. Try to write whenever you can, whether through a diary, Odyssey posts or essay competitions. Good luck!