Start writing during the research, as soon as the basic structure is clear.
The first step is to formulate outlines.
List all hypothesis, points, data, results, and many more, on a piece of paper.
Organized them into some storyline.
For each part of the story, try to put in some simple details. (No need to write abstract at this point.)
Hand them to advisor and get feedback. Repeat untill everyone agree on the outline.
I love this part of the paper:
Do not, under any circumstances, wait until the collectionof data is “complete” before starting to write an outline. Noproject is ever complete, and it saves enormous effort andmuch time to propose a plausible paper and outline as soon asyou see the basic structure of a project.