The best advice I received that helped me actually finish my novel was just hammer though the first draft all the way to the end without stopping and no looking back. Besides writing a lot of run on sentences I ended up with a novel that was over 1000 pages.
The second best advice I received was, cut the shit out of that thing. With a chainsaw.
That is very important advice for me. I put a lot of science in my science fiction. But it turned out the extra 600 pages of data dumps that explained how my FTLs worked, or the anti-gravity, or the AIs worked didn't forward the lot or develop character.
Start with a chainsaw, then a butcher knife, then a scalpel. (Then write more to sew up the wounds)
--I had to be brutal. But in the end, the story is way better for it.