Have you resolved to document more of your classroom experience this year? Or do you want to start making some more organized reflections? Let me offer some unspoken policies about how I operate around here. Maybe these will help you find your own voice. This is not some set in stone set of rules and feel free to ignore one or any of them, but it's the pattern I've settled into.
Write about the good things. A lesson that went well, a positive moment in your career, or a positive development you've made in planning something long term. If you're going to be negative, make it about something that was in your control. A procedure that could use work, an end product that's missing an extra something, or a better seating arrangement. Being negative has its place, and I certainly write about lessons that don't go well, but the intimate ins and outs of events on your campus may not be best suited for the internet at large. Dealing with local issues is usually best done locally. I have work place ups and downs, but this isn't the place for them.
I write up lessons and projects that I do throughout the year. I include some information about what happened before, what the goal of the project was, and how it might be an iteration of a version that came before. I document lessons so I can track their evolution over the year. Nothing pushes you to better ideas than looking back on the ones from last year and seeing what can be done differently. These are the bulk of my posts and done for my benefit primarily. They help me remember things for school years in the future and help me compile evidence for end of the year appraisals. If someone wants to see how I'm making use of Chromebooks and they didn't happen to see it during an in person observation, I can have 6 links ready to go in 5 minutes because I spent the year keeping track. Since starting a site, submitting stuff for appraisals has been an absolute breeze.
I keep the opinions to things I have control over. I have opinions on lessons I gave, what was done well and what was not. I have opinions on content, what's important and what could be done better. I have opinions on curriculum, and how it can be worked through better. I also have opinions about local on campus issues, but again, local problems are best dealt with locally. The internet is not the place for me to go on a rant about class size, or cafeteria menus, or whatever. Unless it's "I tried the school lunch fried chicken and let me tell you, WOW!"
I don't write up stuff in exchange for money. I don't write up stuff because an enterprising ed-tech person e-mailed me about it. If I discover or am directed to a product and I believe in it, I'll write about my experiences. I also don't have intentions of offering stuff for sale or taking donations. I'm in this for the betterment of my practice and the practice of others.
Lessons and projects are great, but I also play around with themes. Maybe I do a series on Pre Cal lessons that have worked well. Maybe I talk out loud about a new way to organize a class. Maybe I make a post about what's inside my classroom closet (which has totally happened and probably needs a version 2). There is no set requirement about what makes something worth writing about. If I'm in the mood to write it up, it gets written up.
I am the primary consumer of my site. You will be the same. Write what you want to write. Write what's interesting to you at the moment. Write what will help you the most. If you need to write up a million lessons to work through some things, do it. If you want to write about classroom furniture, do it. If you just want to post a daily picture with a caption to help you remember sequencing or something, do it. Your platform is yours and it should please you the most. If other people start to enjoy it, that's a bonus.