How to analyse deeply a game (without an engine)?

I just wonder if there's a way to improve at the moment of analysing the games after we've finished.

It could be of great help analysing my games and really knowing what my mistakes are without looking to an engine. I want to found my mistakes by myself and not just blunders or calculation errors, but more deeply like strategical errors, positional disadvantages, etc.

Have a fun day. Leave whatever opinion you have. 

Opening Principles:

1. Control the center squares – d4-e4-d5-e5

2. Develop your minor pieces toward the center – piece activity is the key

3. Castle

4. Connect your rooks

Tactics...tactics...tactics...

Pre Move Checklist:

1. Make sure all your pieces are safe. 

2. Look for forcing move: Checks, captures, threats. You want to look at ALL forcing moves (even the bad ones) this will force you look at, and see the entire board. 

3. If there are no forcing moves, you then want to remove any of your opponent’s pieces from your side of the board. 

4. If your opponent doesn’t have any of his pieces on your side of the board, then you want to improve the position of your least active piece. 

5. After each move by your opponent, ask yourself: "What is my opponent trying to do?"

Middlegame Planning:

1. Expand your position:

a. Gain more space.

b. Improve the position of your pieces.

2. Decide on what side of the board to play.

a. Queenside: a-c files.

b. Center: d-e files.

c. Kingside: f-h files.

Compare, space, material, and weakness(es)

Play where you have the advantage.

3. DO NOT HURRY.  Regroup your pieces, and be patient. 

What you do when you do it by hand, is try to find the exact moment the evaluation changed.

So for example lets say you really liked white's position on move 20. Ok, so now you work backwards one move at a time trying to find black's bad play... sometimes you find out that there was no bad play... and so the position on move 20 was actually equal. Of course the reverse happens as well. Something you thought was equal during the game turns out to be bad/good for you. Moves you thought were bad turn out to be good, and vice versa, etc.

And if you're doing it without an engine, I'd say there are two main modes. First is objective/analytical mode. You try to look only at the best lines.

Second is more like creative mode. After you think you've done a pretty good job analyzing, try to think of totally new or different ideas. The motto here is "it doesn't have to be good, it just has to be interesting." Don't just do it in your head. Be sure to have a board set up, and just feel free to look at all sorts of interesting moves, no matter how bad they might be objectively.

Yeah, well finding them all is impossible on your own.

What players did in the old days, was publish their analysis. That way others could point out things they missed. Even then they didn't catch everything of course, but the point is you can't expect to find all the errors by yourself.

He's right about that.

Well, our own analysis may not be perfect but you might Verschlimmbesserung ("attempt to improve that makes things worse than they already were" according to Urban dictionary.) Who knows? However, it is possible to analyze a game. If you know other variations like two, that's great but @Komodo knows a lot more than us. You can expect errors from yourself if you analyze with the computer.