For those who have kids, one of best ways to increase children's developing writing skills is to write together. Any time you sit down to write a list, a letter, or an email, invite your child to accompany you with your writing. You can also help your young one write letters of their own, which will help them with everything from grammar to sentence structure. Keep a dictionary and thesaurus nearby; this way you can learn new words together.
For academic writing, the five paragraph essay is one of the most common formats. A five paragraph essay is comprised of an introduction, three supporting paragraphs, and a conclusion. Within this structure, arguably the most important feature is your thesis, which is your overall subject or argument. The next time you find yourself writing an essay or paper, try writing out numerous thesis sentences before choosing the best one. This can be helpful after the rest of the paper is finished or before you begin because it requires you to be specific about the intentions of the statements and points you're intending to write about.
For writers, taboo topics can be difficult to write about. This is true for nearly all types of writing, from non-fiction, to fiction, or poetry. Choosing a topic that isn't glamorous or cool can actually enhance your skills and challenge you to find an interesting angle. Consider topics that you don't feel comfortable writing about. Try selecting characters or motives that you find morally despicable in order to create a personal dilemma in your writing. Help your characters redeem themselves by sharing insights and developing back stories.
For fiction writing, choosing characters outside of your writing expertise can strengthening your writing. One way to do this is to experiment by writing characters who are different from your own gender, race, age, religion, family status, etc. This forces you to experience a story through someone else's eyes and create a three-dimensional character based on how you perceive their life.