I think some time ago I somewhere read that there are a few writers here on the forums. Anyway, I'm looking myself to get into writing. Practically want to specialize in crime novels about Russian organized crime. Any tips how you should properly write a good book and maybe if you wrote one yourself, say how was your first book you wrote.

1) Research, research, research.
2) Read poetry and novels that have nothing to do with your own subject.

That's damn good advice actually. I'd add:
(3)Start with short articles(i.e., St. Petersburg in 1998).
(4)Just do it-don't be frozen. With effort, anyone can write something decent and interesting.

I tried to write a book on something unrelated to this kind of stuff.

It became a never ending book on the subject I wanted to write about?

I asked someone about it he said the word "scope" I will let you guys tell us what he meant by that?

Currently so far have bought few books in English that I read. Have been noting down some scenes, like short stories that I plan to put in one big.

Some movies are made from the thing you want to do.

It has some characters or subject. Then they take a lot of different scenes and they call that a book or a movie. It is not really a subject with a beginning a middle and an end.

Tarantini make movies like that. Inglorious bastards and pulp fiction. Sergio leoni when he made once upon a time in America.
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When I was trying to write a book I had too much shit in the book. I had no idea how to end it. Scope means write about an area of the subject you want to write about it not the entire subject.

Is it possible to make a living writing true crime mob books?

Probably not I have a friend who writes all kinds of soccer new papers and soccer magazines. They go out of business faster then he can write them.

I think if you're really good at writing in this genre, then yeah.