The best way to improve your art form is to make a lot of crappy art.
If you want to write better, keep writing crappy stuff until it gets better. If you want to preach better, keep preaching crappy sermons until you get better. If you want to write great songs, keep writing crappy ones until you get better. If you want to do any form of art better, keep doing crappy art until you get better.
If you don't keep doing it, you will never get better. You have to push through and not give up. You have to do more and more...use deadlines and false expectations if you have to. Write a sermon every week even if you don't have a pulpit to preach from. Keep writing an article or blog post even if no one is reading. Write a new song everyday...especially bad ones in order to get better.
Check out this video (via Hey Whipple)