Trying to sum things up: 1.) Try to be concise Good luck! W.
I agree with Europeforvisitors; it also depends on the "personality" of you site, I got one that has almost exclusively pages of 2000 plus articles - it's a hobby-site, but does surprisingly well.
2.) Stick with a language you are familiar with or request assistance from native speakers
3.) Split long articles into several shorter ones
4.) Or, if it is too long, structure it well with many paragraphs, sub-headlines
5.) Don't forget to start with an "abstract"-style paragraph in which you explain what information you find in the following lines (which works only if it's a topic that people will enjoy reading long text about, eg some hobbies).
Trying to sum things up:
1.) Try to be concise
Good luck! W.