Ehh, I don’t really see much of a right or wrong way when writing a review. Much like making a film or any other form of expression, as long as you get out what you are wanting others to know about yourself, the film, your opinion of it, etc. - then you have done it the right way. Is there a formula to it or a series of rules? I wouldn’t think so. I never have followed anything like that, maybe with interviews, but opinions are simply opinions. Things like cinematography, sound design, acting, plot development and character arches are to be considered and factored in - but in the end it all comes down to staking your claim as to why you do or do not like something. Sometimes it goes beyond those things. Maybe it’s just a feeling, maybe it’s the pacing, etc. It’s all about describing that and putting it to text for others to indentify with.
There are a few personal things I like to try and tackle when I write a review. The first thing I do is pick my audience. No matter what the film, no matter how great or how bad it is - someone is going to have a differing of opinion. I like to try and select the audience who will best appreciate the film and try to speak to them. That way you can at least margin the odds somewhat in favor of those who might enjoy such a film. I also try to avoid hype. Sometimes it is hard when you feel so passionate about a film (I’m reminded of the first time I saw Blue Spring, I went nuts for that flick and wanted everone on earth to see it), but in the end it’s better to express how great a film is and then soften it out by the end of a review and let them know that no flick is perfect and not everyone will see what I see in it. What about if the movie is terrible though? I don’t know… I guess I’m a glass half full kind of guy, because these days its hard for me to watch a film without finding at least some good merit to it. The only flick I can still think of that was just so dreadful I couldn’t imagine ever watching it again was Blackenstein - even then though, there are those who would love to see something so terrible! Bad filmmaking is bad filmmaking however, and shots with a guy just walking away from the camera that take up 180 seconds of screen time (repeated three or four times over) is just inexcusable and you have to make note of it.
I also tend to speak alot about myself and any journey a film might put me through. I have been criticized for that in the past myself. One time a writer from Rue Morgue proceeded to lay into myself and several of my friends (also with review websites and such) because of this. Trolling us and saying we spent more time talking about what flavor of popcorn we had at the theater than we did the movies (granted, that’s a good burn, but honestly - who goes to the theaters anymore!) going so far as to say a great review takes up no more than 300 characters. Maybe he’s right, I don’t know. I do know that the same guy now has a big article in Rue where he goes over about 1500 characters and more often than not talks about the nachos and cold beer he had while viewing the flicks he’s writing on. Yet, I digress!
A one sentence writeup for a movie is still a review, and a 1000 word editorial is as much the same. I think the best you can do is simply try and put into words all the reasons you love a film or all the reasons you do not. In the end everyone has an opinion, but if one or two people can take what you have put into words and begin to grow more as a film fan because of it then that is what it’s all about. I wouldn’t say there’s any pattern people need to follow, but finding a reviewer you identify with and even when you disagree still respect is a good idea. Read their style and take note of the things they find important in a film and whether you agree or disagree. Doing that can sometimes open your eyes up to filmmaking in completely new ways. The first two reviewers who really caught my eye and made me start looking at these films I loved in a different way were Mike Bracken and Chris Stewart from IGN, who used to have a lot more on their site but it looks like those reviews may be lost. Sucks, guy is very witty and a fun read.
Sorry, went on longer than was expecting there, just my two cents 
