Issues in Writing

I have some issues in writing. I don't mean issues with writing, in the sense that I think writing is a bad thing. What I mean is that I have personal failings that keep me from developing my writing as I should.

One is procrastination, which plagues me in a lot of areas besides writing. I think with writing, though, it is a bit of fear--fear that my writing won't be good. Then there is just downright laziness. I don't do the research to write a good, intelligent piece of writing. I don't write drafts and then edit them so that my writing is coherent and has points supporting what I am trying to say. I tend to just sit down and write off the top of my head, like I'm doing right now.

What do you do to get yourself to sit down and write, and to put in the necessary work to produce a good piece of writing? And while we're at it, what do you do to overcome writer's block--to decide what you want to write about and then narrow the subject enough to make it an interesting, informative piece of work and not just a ramble about a very general topic?