Writing tight, or writing articles tight, is an term used by editors to keep articles short, sweet, and to the point. When you are writing for a newspaper or a new article, you want to keep your information as minimalist as possible. You are not writing a research paper or a short story, you are there to report the news.
This is a skill that may take years to perfect; however, you can practice easily by using a utility that will count your words for you while you are writing. If you can get the point across in 200 words or less, you are doing great. Sometimes, you editor will ask you to write an article that is in so many words.
Also, in your writing you want to stick to the S-V-O (Subject, verb, object) style of writing. This is the best way to get your point across quickly and accurately. More more information about that, check out this article on S-V-O.
It is sometime difficult to convert from being person who writes blog posts, to a person who just writes new articles and visa-versa. For blog posts, it is better to have 500-1000 works; whereas with news posts, the less words to get the point across the better.
For example, this article was 222 words.