I would say practice makes perfect. If becoming a better writer is important to you, try to build a regular practice where you write each day and build some sort of feedback loop into this process to help you improve the quality.

There are plenty of pedantic people spending their time on forums who will naturally correct you if you make an error in your writing.

Writing a blog entry once a week and asking a friend or two to review the draft might be another way.

You're not doomed to anything if you take on a mindset where you believe that you can and will improve.