For most of this year I've been part of the Advanced Writing Course run through The Creative Hub in Auckland. Being part of a writing group is a must (in my opinon) for writers. It's great having a group of other writers reading parts of a work in progress and giving insightful feedback, which the CHubbers always do.
There are always those parts of your work you have a niggling feeling about, but just can't see what isn't working, and also the bits that you think are great, but others, not so close to the work, can see the gaping holes in the plot.
Being part of this group has also allowed me to read great work from the other writers, some in genre's I wouldn't otherwise read.
For any writer who isn't part of a writing group I'd say, go and find one, or failing that, start one yourself. It's brilliant spending an evening talking about writing and writers without boring everyone else in earshot.