The thing I find hardest about writing is plot (or possibly structure, or possibly both); so this year my main aim is to get better at constructing a story which hangs together well, especially at novel length.
Historically I've tended to just get on and write, and then fix everything in editing; but that means that editing can wind up looking like a full rewrite, by the time I've corrected the structural issues that result (for me) from writing that way, and fixed up all the gaping plot holes. I do really love the thing that happens when I'm getting words down onto the screen at speed and letting my brain carry me away; but I'm also fed up with a first draft that looks quite so unformed.
So I've been reading a lot about plot and story structure (best book so far: John Yorke's Into The Woods, though 'best' here may just mean 'fits best with my brain', and trying to use all of it to write an outline for my next project, which involves London and dragons and too many secrets. After an initial flaily period it's starting to come together, and I'm looking forward to getting cracking on the writing. But I'm determined to sort out the holes I can still see first, this time, rather than putting them out of mind and 'just writing'. So it might be another few days yet.