My son's third-grade teacher has a classroom poster that I love. It's called "10 Ways to Be a Better Reader." It then goes on to list the 10 ways, each in a different color. The part I love is that #1 to #10 all say the same thing: READ.
It's the same with writing. To be better writers, we must read...
1. Published picture books: I've known this for years, but have only recently taken it to heart and begun regularly checking out and then reading bags and bags of recent picture books. I'm also currently participating in Reading for Research Month (ReFoReMo), which has been a fantastic way to discover new books.
2. Other people's manuscripts: Everyone says that you need critique partners to help you hone your writing. After all, other people can see problems and solutions that you can't in your own writing. But, there's also benefit to critiquing other people's work. When you do so, you see what other writers do well (and where they need work), which can inform your own writing.
3. Blogs: There are so many blogs out there about writing, by writers and for writers that it would be impossible to keep up. Two that I especially enjoy are Susanna Hill's Blog (for the book reviews, contests and other community-building activities) and Literary Rambles (for the informative interviews with agents). Pick at least a few and try to read and comment regularly.
And of course, while you're reading, don't forget the most important thing: keep WRITING!