Writing is undeniably one of the most difficult academic skills to obtain and perfect. We're not talking about penmanship—that's a question of motor skills and coordination. Writing is catching ideas to put them in place on paper. It's a bit like butterfly hunting, except that the net is your brain and you never get to be as neat as holding wings in place with pins. Ideas (and words) have a habit of squirming all over the place, even when you think you've got them just right.
They keep squirming because ideas don't die. At least, they shouldn't: a dead idea is no idea at all, and once yours stops moving you know you've killed it. The trick of writing well is getting your ideas to stay more or less in place without draining the life blood out of them. Such skill takes dexterity, precision, and carefulness, and none of those come naturally. Even if you have some innate talent, practice and sharpening can only make you better.
Books in this section are designed to help students (and parents) hone their writing abilities. People too often have the impression that writing is just about facts, or about simply telling a story, or about describing something. All those are involved, but writing is really about conveying meaning. Bare facts, plot points, and physical details don't mean anything without context, they just are; it takes a writer's ideas to make them significant and to use them to tell readers something about the world and life in it.
For example, let's say you've been assigned to write a paper about your dad. You might describe him this way:
My dad is 6'2", with black hair and a beard, and big hands. He likes to read a lot of books, especially books about theology and history. He works in a hardware store. He watches old science fiction movies because they are funny and weird. He is an elder at his church, and he leads a Bible study on Wednesday nights. I admire him very much.
But that description makes us wonder if even the author really knows his father. It could describe any number of men, and is therefore next to meaningless. To tell us about your dad, you'll have to tell us what he's like and how you feel about him, not just about his statistics. A better description might go this way:
If you could talk to my dad outside of work, you'd think he's a professor. You might think the same thing when you see his personal library: several thousand volumes strong, covering every topic from Bible commentaries to the history of food and drink to obscure novels from the 1920s. But he's not a professor, he manages a hardware store, and does all his reading in his spare time. He's also a church elder and Bible study leader, so where he gets the time is a mystery, but he remains one of the best-read and wisest men I know. His love of old sci fi movies is a little weird, but given his strengths I'll forgive him his weaknesses.
This one's longer, but it really tells us something both about the author's dad and about the author's feelings toward his dad. In other words, it's meaningful. How does the author achieve this? Two ways: he knows what he wants to say (idea) and he knows how he wants to say it (style). Too many beginning writers (and plenty of veterans, for that matter) jump right in without first considering either of these things, and their writing comes out sloppy, confusing, and lacking spirit.
An idea is the soul of good writing; style is the body that gives it form. In the above descriptions, the author is trying to convey his admiration of his father, but only in the second description does he really succeed in conveying that idea. The difference is both that the idea has been sharpened up (made less general) and that the style suits the idea. The style of the second description is concrete, specific, vivid, and clearly demonstrates the author's affection for his Aged Parent.
How does one manage to write like this consistently? Practice, practice, practice, reading good writing, honing your logic and critical thinking skills, practice, and studying the nature of the English language (assuming you're writing in English). You'll have to take care of all those on your own, but we can help with the last one.
The books you'll find below focus on the style aspect primarily, but it's not really possible to separate ideas and style when it comes to good writing. Without a good idea, the style is empty and whatever has been written is a waste of the reader's time; if the style is lacking, even the best ideas will be incomprehensible or at best confusing. A classic like William Strunk and E. B. White's The Elements of Style addresses both issues and shows how they're dependent on each other.
There are more specific titles, too. How to Write Irresistable Query Letters will help you present your writing to editors in an appealing and intelligent way. Eats, Shoots & Leaves is devoted to helping writers understand and use punctuation correctly. The Art of Fiction by brilliant American novelist John Gardner is full of sound advice for organizing, plotting, and executing the stories you want to tell.
Just because you've mastered style doesn't mean you have well-thought-out ideas. Likewise, just because your imagination is prolific and vivid doesn't mean your writing will be. To write well you must master your thoughts and your language mechanics, and you need help and guidance to do both. These books are offered to provide such guidance, though it's essential that, if you hope to be good at writing, you write as much as possible. Not all of it will be good: but you'll never get good unless you get through the desert of cluttered ideas and sloppy style first.