I usually just wing it but make sure it's organized because I hate it when I feel like my entries are all over the place. I sometimes know what I want to talk about beforehand though.
My blog is mostly a diary (hence why it's called The Diary of the Short, Fat Cyclops). But I do sometimes plan blogs out. I have a few things written as a just in case I have nothing to write about that day sort of thing. I like to post content at least once a day to keep it fresh although it doesn't always happen.
Mainly depends on the subject. Sometimes if it is something a bit deeper I will start it and add a little bit to it until I feel like the thought is complete. I also will write posts and schedule them to be posted in the future. More often then not it is because I have 2 really good ideas in one day but I don't want to double post. Drags things out a bit.
I always have a notebook where I write topics/trends that come to mind. I look at it when I don't have anything for the day to kind of jog my thoughts sometimes. Sometimes a event like Kanye and Joe Wilson wilding out produces gems
I usually submit a rough draft to my teacher a week before the blog is due, and he makes corrections and suggestions in red ink. Then I do my best to follow the 5-paragraph essay structure, with my big idea at the top, narrowing down to my thesis statement in the introductory section.
As other people have said, I do a little of both. Sometimes I will just open it and write, other times I have something specific I want to gripe about, or express and opinion about, and I make a post-it to blog about it later.
I think I do half and half. Although I'd say the majority are planned. I dunno, I think they are. I keep a notebook with me 24/7 so that I don't forget anything. Does that count as planning???
In Life: The Juan Thomas Story, I usually preplan a lot of my blogs...like the poems I release, the album reviews, and certain special blogs (birthday, trips, etc.). However, I shoot from the hip a lot too. My life is a neverending story so as it happens, I find something about it to put in black and white.
I wing it. If I have an idea I write it. even if it's twice in less than an hour or not until a few days or so later. Then when I write it I seldom reread what I've written til later. Which means I can end up with typos or missed words that go unnoticed. Then sometimes I end up with a post that I don't really know how I want to word it. Those I wing it and go back and reword it and add or delete things. Those always sound less Real and less Me. So I try not to do that too much. I like genuine better, even if I end up repeating myself or making minor mistakes. That's how I am in real life too. :)
Rarely I do have things that I want to write about that I will take the extra time to figure out exactly what about it that I want to write. Like my next post. It's not someting I was comfortable writing in my last blog because I knew of certain people who read now and then and I did not want them to stumble across it. So this blog I can write without worry they may show up, But it's putting myself out there more than I normally do, and... I suppose you can say vocalizing something I normally wouldn't. But I want to, so I;m going to.