How to Prepare Chess Openings?

 What are the guidelines to know and to study on creating your own opening repertoire on chess?

I only got few and also the basic ones such as:

* Development

* Typical Pawn Structure that will Arise

* Endgame Strategy for both sides.

Please suggest for more guidelines and basic fundamentals! :D

While I think going over old master games of your system can be good.

I don't even study lines if I get a playable position with normal developing moves. I usually do some rough categorization like the following:

Is it an advanced line/exchange or regular? Broad centre or small? Gambit?

Where are the players castling?

Is any alternative development/early attack dangerous?

It can help to have some miniatures as well. Perfect games don't show the typical mistakes people make.

Depending on the complexity of the opening, I'm going to use a minimum of 3 main ideas. If it needs to be more concrete than that, I also look at more specific lines. I would play the Spanish any time, but you don't just play the Rauzer or the Sozin on the fly.

That is really all I do, since most people are out of book before move 15 and I don't get very much out of it most of the time. I just like to be developed while I have some idea for the middle game plan. The only thing I dislike is being really passive or downright clueless.    

Most important for me is: Testing it. Obvious moves are often far more annoying than book lines. I often end up with a whole shadow tree or ''normal people's theory.'' This is almost never played by strong players, nor is it covered in learning books. If I just know how to survive this I am fine. I also learn a lot from the position like this.

You should choose according to what are you playing for. If you are playing for a win, you'll need lines which lead to a position where you stand better than the opponent. If you want a draw, there are other openings that will allow you to draw more easily no matter that you don't come up with such an advantage first. Sometimes you may play an opening that's not sound but requires an exact refutation, and if you're more familiar with it than your opponent you'll either get a better position or get more time (if your opponent is searching for a refutation over the board). Have a look at the known openings (and mainly at the positions which occur after them), choose which of them you want to use, then study them in detail and you should be fine.

This video should be very helpful, and it is free.

http://www.chess.com/video/player/pawn-structure-101-every-opening-explained