I write reviews in five sections. The first is an introduction, providing backstory on the game. The second is story, where I summarize the game's plot and then describe my thoughts on it. The third is gameplay, where I describe the game's systems and mechanics, and any flaws in them. The fourth is presentation, where I talk about the game's graphics, music, and voice acting. Finally, I have a concluding paragraph that summarizes the review. I do give the game a letter grade based on the number of flaws I find, but that's probably the least important part of the review.
I can't say any of the sections are more important than the others- story, gameplay, and presentation are equally important for making a game enjoyable. If one is lacking, the entire package suffers as a result.
If I'm posting an older review, I'll say so in the title, and I might include a small section before the review if my opinion of the game has shifted at all since I reviewed it. I also try to review a game as soon as I beat it, which on average takes me a month.
I should have my first review up on the blog soon.