Now I go to the forum and see a lot of different information. Even if I want to write something useful, it's always on the forum. How to raise a rank in such a situation?
The only way is to out shine the previous writer by writing something more useful/meaningful to help better the community. There are many accounts now on bitcointalk and they all are searching for merits. You can always write something useful even if it has already been answered by previous commenters, still give your view on the matter and you might just impress someone with free Smerit to merit you. And if you feel what you have to say is not meaningful enough, move to next post and drop your view to avoid comments been deleted.