There seem to be two basic theories when it comes to writing and they are as follows:
One: if you're not feeling particularly inspired or creative, then don't write. It's better than producing utter crap. Lord help you if people actually read it and think you are a terrible writer.
Two: even if you're not feeling particularly inspired or creative, even if it's raining outside and your favorite pen is out of ink, even if you have a toe cramp or you'd rather be doing something more intriguing like cataloguing your extensive stamp collection, write. For God's sake write. Free flow even if you feel like holding a pen is painful and sentences are coming together slowly and dreadfully four words at a time. Just keep going. You may read it later and think: "Wow, this is some hot garbage." Or you just may surprise yourself.
In the absence of consistent blog posts my rainbow colored composition notebook has gone with me everywhere. While some days on the train I would rather listen to music and fall asleep leaning on the person next to me, I write anyway. On my break when I would rather skip down to Corner Bakery and buy a monster cookie, I'll write instead. Slowly but surely, I think I'm having a break through. Words, ideas, plots, characters, they're all starting to form on the pages like some congealed primordial brain goop. It isn't pretty but it's mine, and it's coming together.
The best advice I can give you on my own theories of writing is that Writers Write. Regardless of how messy or nonsensical. If you want to be a perfectionist, become an editor.
Writers Write. Period.