How to build an opening repertoire

One hundred days of Adult Chess Improvement #25

Many coaches advise that the amateur really shouldn't worry about studying the opening. What they mean, of course, is that we shouldn't spend hours and hours memorising long lines from opening books or videos. Sound advice. But equally we do need an opening repertoire. A series of openings that will allow us to get a playable position where we have a good idea of the plans for both sides. 

How do we go about building this repertoire?

I would argue that the key word is "slowly". We need to create our repertoire over time. It also needs to be written down (whether on paper or digitally). How do we do this?

Step 1: Write out a skeleton repertoire that covers all our opening choices.

Step 2: Every time we play a game (this include all forms, even blitz) check the opening and update your written repertoire.

Perhaps it is time for an example.

 My first longer game featured a move that I hadn't seen before. In the position below:

White has just played 9. Bg5. The move given in all references is 9. f3 and Bg5 is not considered. 

I wasn't sure how to evaluate the position - was this inspired or just a mistake? My quick engine search gives Bg5 an evaluation of -0.83  and the standard f3, as +0.83.

Unable to decide what to do, I played 9. .... c6 aiming to transpose to more familiar territory. The computer suggests immediately challenging the bishop with 9. .... h6. This didn't even enter my mind! Why? I suspect that it is because I was thinking about following "book" lines rather than thinking concretely about the position.

For the record, the following are three roughly equal variations:

9. Bg5 h6

A. 10. Be3 Nxe4, 11. Nxe4 Rxe4 - white has some activity for the pawn but probably not quite enough.

B. 10. Bd2 c5, 11. Nc2 Nxe4 12. Nxe4 Rxe4 - again, white probably doesn't have quite enough for the pawn.

C. 10. Bxf6 Qxf6, 11. Ndb5 Na6, 12. f4 Qd8 - white has more space but the open position should suit black's bishop pair.

Analysing this continuation in the context of a game (and writing it down!) makes it far more likely that the variation will be remembered and understood. Obviously this is a slow process, but one with much better chances for long term success.

A Chess Mistakes

A1 Knowledge 

A2 Skill  

Miscalculated a pawn ending ***

B Mental Errors

B1 Thinking 

I treated a capture as if it were a forced move *

Difficulty in visualising a position during analysis**

I didn't consider all the attacking options - fixated on a double check*

I didn't consider all the defensive responses - I missed interposing a piece**

I didn't consider all the defensive responses - I didn't analyse all escape squares*

B2 Psychology 

I played a move too quickly without checking all available replies ***

I got carried away with my "solution" *

I recalculated and then rejected the winning line which I had already seen*