Many of my students are stumbling over the new Writing & Language section not because they don’t know the rules of grammar, but because they are unfamiliar with the rules of style. While grammar and style work hand in hand, school tend to focus more on clear cut grammar rules rather than delving into murkier style codes.
Fortunately, William Strunk Jr. and E.B. White (author of Charlotte’s Web and Stuart Little) did some of the heavy lifting and wrote the first version of this Style Guide nearly 100 years ago. Since then, the volume has been edited and updated, and this slim volume (only 70 pages) remains a standby for writers of all levels.
I would encourage you to pick up a copy if you are unclear about active versus passive constructions, successive loose sentences and why shorter is better. The writing is clear and concise with plenty of examples to illustrate the points made.