People take a lot of approaches to topics. Everyone has their favorites to write and their favorites to read. Everyone also has their most-hated. I'll talk about this a little. Obviously I can't even mention every approach, but there are several basic approaches people seem to use the most.
I am giving myself a fake topic to use as an example. It will be "lemons."
1) Discuss your feelings about the topic and what the topic makes you think about.
This would be the entry where someone talks about the different meanings of the word lemon. They would talk a little about the fruit and why they like it or dislike it, and maybe a little about cars that don't work. Then they might mention Liz Lemon. This is probably my least favorite approach to topics. While some people can really take this in a deeply personal and interesting direction, I generally feel like this is preparation for writing, and not writing itself. I tend to find these entries to be strongest when they really veer off into stream-of-consciousness writing, because that is usually the only way that they get a personal touch.
2) Pick one specific aspect of the topic and zero in on it to write an essay, either descriptive, personal, or persuasive (I am counting rants here, too)
Here, the person might remember a scientific article that they read about lemon seeds, and reinterpret the information they learned from that article into an essay about their opinion on the scientific claims of the article. This can be a really interesting way to approach a topic, although it's one where you have to be confident you will pick an aspect that not too many other people will pick (or that you will do it better than everyone else, which is not so much confidence and more arrogance considering the number of awesome writers who are out there). It doesn't happen every week, but sometimes there will be a lot of people who pick the same aspect to zero in on and then only the ones that are really unique or really well-done stand out. Another thing that is important in this approach is research and fact-checking. Even when writing a rant, if it's being written for other people to read, make sure you have your information right. One thing that can take away from non-fiction for me is if it's not well-researched.
3) Pick one specific aspect of the topic and zero in on it to write a memoir or personal narrative style entry.
This is like #2, but is more deeply personal. This writer might relate a story from childhood about the first time they made lemonade. Because of that, it can often succeed where #2 might fail, because your personal experiences are more likely to be unique. I do think that some people are better at relating personal experiences in a way that sets them apart, but I always like entries where I get to learn something about the person writing it, and these are usually the easiest posts to do that in. Even ones that don't impress me with their writing often make me like the writer more as a person (unless they write, say, about how proud they are that they squeeze lemon juice into puppies' eyes.)
4) Pick one specific aspect of the topic and zero in on it to write fiction.
Like #2 and #3 but this is the one where the writer writes a fictional story about lemonade-making. This can be a good way to achieve the same kind of "feel" you would get in #3 while not necessarily writing something too intensely personal, or when you don't actually have a personal experience to base it on. I am a sucker for good fiction but I am much more highly critical of fiction that doesn't meet my personal standards for "good writing" (whatever those are) than I am of non-fiction that doesn't. I think a lot of people feel that way so it can be a risk.
5) Approach the topic metaphorically.
Here, someone might think about the sourness of lemons and write an essay or narrative about a sour aspect of their life or a time when things turned sour. I really like when people take this approach because it shows a certain amount of creativity and risk in still relating to the topic while having a more tenuous hold on it, but it doesn't always work and for some people, it's not always clear how it relates.
6) Take a bye.
7) Combine any of the above approaches into a single entry.
In this case, someone might alternate paragraphs of personal narrative or fiction about a lemon-related experience with scientific fact about lemons that bolster the "moral" or "punchline" of the story. These entries can be rich and complex at their best and meandering and pointless at their worst. While when someone does the metaphorical approach, I can give them the benefit of the doubt that THEY see a connection even if I don't, if I don't see the connection and they're trying to draw the connection on the same page, it can really push me out of the story. At the same time, if it's well-done, it might make me see a connection I would never have seen on my own.
I know, I know I left out "write poetry" and a few other formally experimental styles people have played with. But on some level, even those formally experimental styles are usually based on one of these approaches. Most of my comics were either personal essays or fiction, even if they were personal essays or fiction in graphic form.
Picking an approach can also be part of how you approach the topic. You can think about whether the topic is better-served through an essay or through fiction or through a poem. Sometimes the meaning of the topic will lend itself better to one or the other. Sometimes, you might even go so far as to feel like it would be in poor taste to write a certain approach to a topic (I felt that way last season about "Hyperbole is Literally Hitler" and didn't feel right making a comic about it, although I didn't let that affect the way I read other people's entries, just how I wrote my own), while other times, you might feel as if there is only ONE approach that could possibly work, even if you don't know what you're going to do for it (Last year, for "Salt of the Earth," I knew I wanted to write non-fiction but I looked at a bunch of different subjects for it before deciding on one). I definitely love seeing writers who try all different approaches or combinations of approaches and don't use the same approach every week, although there are some writers who are masters of a single approach and are able to use it without making you feel like you're reading the same thing you already read.