You can write blogs on just about every topic. However, any blogs incorporating overt examples of these (and potentially other) aspects will be deleted by admins and may be followed with a ban:
Pornography, whether photographic or cartoon
Hateful conduct, including bullying, racism, slurs against individuals or classes of individuals, or doxxing
Call for violence against individuals or property
Encouraging self-harm or the harm of others
Calls for or examples of committing illegal acts
Plagiarism of other content in part or whole
If any actions are deemed criminal in nature, the proper authorities will be provided with the content as evidence, upon request.
Having a blog featured is a way to increase visibility to all members. Not all blogs requested to be featured will be accepted, but it is possible to increase the chance by incorporating these into it:
Topic of public interest This could be a current event, a movie review, a song parody, or any of countless other topics. When writing this blog, thing about appealing to a wide audience. Sometimes, a controversial topic may receive more engagement, but try approaching it in a respectful manner.
Clear focus Try to stay on the topic, rather than rambling on tangents or flooding the body with spoiler tags or other aspects that could frustrate a reader into losing interest. Also, give enough details so that the reader will not wonder the purpose of the core topic.
Appropriate length A blog that just a few sentences long will likely not be featured, as it would be lacking in content, but a blog written like a novel may be too long to hold reader interest. Try to aim for content that will take about 2-5 minutes to read. If your content will be much longer, there is nothing wrong with breaking it into chapters.
Professionally-written Use proper grammar and punctuation. Try to minimize jargon to appeal to the widest audience. Acronyms that are not generally-known should be expanded upon the first use so that readers understand what you are trying to say. If the blog is meant to be persuasive, make sure it contains a logical foundation, rather than fallacies and polemics.
The SDK Community supports several BB Codes, including a few unique ones, to help you make your content richer and easier to read. It is possible to combine many of them for compounded effects by embedding them within each other.