I have been learning as I go along with how to write on here. My first advice is to write down exactly what you are thinking. Never try to write like some one else. Each person has their own style.
Some write shorter reviews with a lot of information, some write short reviews with no information or next to none. Still other write long reviews and say much and others can write long reviews and still not cover everything if that made any sense.
I have been told my reviews are too long and also been told they are too short. So what I do is write the way I feel about what I am reviewing and just do my own thing. You will not please everyone no matter what you do.
If you are new(the older writers will not find this useful) go around the entire site and see where everything is and read some of the star writers reviews to see what is good.
I was asked early on to not write so many reviews at once as I was putting out 2 a day and was told I was blocking others from the top 35. I was not even sure what that was as I had never scrolled to the bottom of the homepage, once I did I found it. Since then I have been trying to space my reviews and wait until several others have gotten on that 35 list before adding another one. Some newbies are writing 5 and 6 in a row and this is not good.
At the current time there is a contest going so those that want to win are pushing the reviews out. Remember the notice we got though that says to maintain quality.
I write simple and in my own words as that is the only way I know how to write. This is my style. Some will like it, some will not. Do not get discouraged if you get a bad comment. Read what it says and follow the advice as it will improve your writing.
Try to include as many facts as you can. For example if you are writing a book review by all means give the authors name and a basic plot, just dont give away the whole story line. Write enough so that anyone reading it can decide if it is a book that they would enjoy.
Some people write in mainly one category and that is fine too. I have been trying out some different ones. Some I leave alone as in the above mentioned book reviews as I do not write them well. By the time I am done reading the book I would be lucky to remember all the characters names so if you know you dont write well in some category then it is best to stick to what you do know.
Also there are some things that may not be familiar to all as we have several countries of people writing so I try to stay away from those also.
Make sure you use the spell check as some will rate you lower if you do not spell something right especially if their are several mistakes in one review, you can edit over and over until you get it right. I do wish the site would have a recommended spell checker such as e-mail clients do but there is always the dictionary.
Make sure you use punctuation, and leave spaces between your pharagraphs as if it is all run together it does not look as well.
I am sure some newbies have gotten timed out while writing as I have and then I copy and paste it back in and again you have to make the pharagraphs or it will be all one. The thing I noticed recently is when you log in if you check the little box telling it to leave you logged in until you log out this will prevent it from happening.
Just do the best you can and keep trying to improve.