It's so easy to find reasons (excuses?) for not writing every day (or at least regularly). Some of the best and most useful tools I've found to keep creative juices flowing are writing exercises. There are many good books out there, some inspirational such as The Woman Who Spilled Words All Over Herself by Rosemary Daniel, some on craft and life such as Writing Down the Bones by Natalie Goldberg, some with a generous number of writing exercises such as Writing Fiction, a Guide to Narrative Craft by Janet Burroway. Of course there are numerous online resources for all the different genres as well . Whether we're writing poetry, fiction, nonfiction; writing for ourselves, for adults or for children, the key is to write regularly.
As we sharpen our writing skills, gain confidence, and start to edit and revise our work, we learn to pay closer attention to detail and turn to sources such as The Elements of Style (Strunk and White), and Eats, Shoots, and Leaves (Lynne Truss) and other books on form, style, grammar, punctuation, and so on.
Finding time to read, particularly books such as those we wish to write, is essential if we wish to grow as writers and keep up with ever-changing tastes and trends.