How I did it: I signed up for nanocamp, outlined it extensively before June came round (I think outlining in that depth was the key I was missing). Then just sat down and wrote at least 1667 words a day. Some days I did none, others varied (my top was 4.5k in a day), but I tried to remain on task.
Thankfully this first draft ended up being around on target of 50k words which I had planned for so I ended the novel at 50800 words by the end of the month. Don't know why I found this so difficult to do before. Maybe I was just ready this time.
This month I'm trying to edit and finding it much more difficult than writing the thing. Also going to try and do a extensive outline for my next novel (considering writing that next month - or I may just stick to editing and try and get this novel finished, polished and ready to send off for submissions by the end of october so I can start my new project from beginning to end on the first of november).
Lessons & tips: Find what works for you. Outlining, or going with the flow. (Turns out I need everything outlined. I thought I was the other way).
Resources: campnanowrimo and nanowrimo communities. Also a spreadsheet to keep track of my words.