Couple of things. If you want to post sarcasm, and you're not sure if it will come across as such, you can indicate it by using fake [sarcasm] [/sarcasm] tags, or putting the text in purple.
Another thought, though, is that you are likely preaching to the choir on many things, so maybe so much commentary isn't required. Although in my case that advice is like the pot calling the kettle black as I have been known to write too much myself on occasion.