What are you "best practices" for writing research papers start-to-finish?

I've been really struggling with putting my second paper together for the past week or so, and was wondering: what practices do others follow so they get their writing done in a more efficient, more timely manner? I'm in computational math, but I don't think the advice needs to come from someone doing math-heavy research. I'm curious, if you're someone who considers themself a good/efficient writer, what are your tips and tricks?