In your case, it's very simple. First, find an author you admire greatly. Then, read their works nonstop while you think about how Godawful yours are in comparison, and about how you should probably burn your manuscript and go get a real job before your family starves becase of you, you lazy head-in-the-clouds disgrace to mankind. I recommend reading FullyRamblomatic.com, Watchmen, or the script to a Pixar movie.
If you overshoot and fall into a depression, just read Eragon once or twice, and you'll be back in fighting shape.
The key, however, is to learn how to critique yourself. If you don't know how, watch all of Zero Punctuation in one go, divide your personality into two parts, assign part two a seperate name, and write while in that mindset. Then have part one-- the 'real' you-- take the piss.