I participated a Scientific Writing workshop last semester. The tips were similar and then I started to use this suggestions. It really works, do it! Write daily, for example I usually start writing in the morning and for two hours, I shut down my phone, say to my friends and colleagues that I had a meeting with my manuscript and only concentrate writing. Here is a little planning tips from workshop: (imagine that you need to write only a paragraph and use timing on the list)
1-Define your topic (What are your questions) – 3 min.
2-Find informations you need (references, statistical terms etc.) – 3 mins.