Different writers have different approaches to their writing. Because my stories are fairly plot-heavy, I prefer to block them out as quickly as possible, get as much of the first draft done at the start, while not worrying too much about the quality of the writing. The aim is to make sure that all the plot lines are working and that they are consistent. As more details occur to me, I throw these in at the relevant places, a bit like putting together a jigsaw, until I'm happy with the overall structure. As this is all done at the ideas stage, I don't tend to suffer from writer's block. If anything, I have to be careful not to throw too many ideas at it. I have tendency to over complicate things, if I'm not careful.
Once I'm happy with the overall structure, I can then concentrate on the quality of writing. I may not have the whole book completed at this point, but I should have enough to see the general direction of the narrative. This is when I do my first (usually) comprehensive rewrite.
From then on, it's rewrite, edit or try to complete, depending on how the mood takes me. And when I've got some sort of finished product, I leave it for a while. At least of couple of weeks, while I do something else.
I need to come back to it as a reader, rather than a writer, so I can enter the final stage: polishing the product, looking for errors, reading it critically.
I'm never satisfied, of course, but at some point you have to stop tweaking. you have to let go and get it out there.
That's when the really hard work begins.
Promotion.
