In the first improvement tip, we conducted a short exercise to help form a subjective assessment of your chess strengthes and weaknesses. Now the hard work starts: annotating your games to form an objective undestanding.
As soon as possible after the game, make notes about your thought processes during the game: Which variations did you calculate? What positional factors did you consider? What strategic concepts did you think about? Did any of your opponent's moves surprise you? Which did you consider to be the crucial moments in the game?
Do this as soon as possible after the game, and be honest trying to capture your thoughts as they were during the game.
The second pass: review the game objectively, and annotate variations and ideas in depth. Note, where you mis-analysed during the game, and where you missed ideas and opportunities. Use your opening books to check for plans and improvements on the line you played.
Finally, the third pass: work through the game with your computer. Has it spotted any tactical shots you overlooked? Is it suggesting lines you didn't consider? Why? Do they look good?
Annotating your games is a time consuming process, particularly if you adopt this 3 pass approach, but your effort will be rewarded.
After you've annotated a few of your games, start looking for common issues: are you making the same types of mistake? Are you struggling with certain types of position? Are you analysing variations well? This information will help you decide where you need to concentrate your improvement studies.
Annotating one's own games is something that was emphasised in the 'Russian School of Chess', check out a work like Alexander Kotov's Train Like a Grandmaster for more information.