Sometimes the best way to ace your writing is to first learn how to avoid doing things the wrong way.
Some writing mistakes are more common than others, and can be avoided if only we learn to recognize them. Take some time to familiarize yourself with these common mistakes.

1. Unnecessarily Long sentences
Casual readers today don't have a lot of time and attention. Unless you're writing literary fiction, you are far better off to break up anything longer than a few lines. Use formatting tricks like bullets, italics and so on.
2. Writing For Yourself
Writing only for yourself is terrible writing advice. The best writers always consider their ideal reader. Crafting an ideal reader will help you speak to one person rather than many.
3. Writing and Editing at the Same Time
Multitasking won't help you become a profitable or prolific writer. Both activities engage different sides of the brain and context switching is just confusing. By all means take out needless adjectives and adverbs but not while writing. Separating these activities into different parts of the day may help you focus.
4. Too Much Explanation
Over-explaining can manifest in several ways, but the core of the problem is always repetition–and it’s usually symptomatic of authorial insecurity.
5. Overly Complex Prose
Used wrongly or too often, complex prose can create distance between your readers and your words–or, worse, just leave them confused.
6. Using Incorrect Grammar
Using incorrect grammar when writing or speaking can lead to unclear communication and miscommunication. Read through your writing to ensure it makes sense to you and whoever it is intended for.