Before writing, I checked for other peoples’ views on how a busy person should prepare? But most of the time they suggest opening repertories which save time. Instead of this I have a different idea that does not involve the effort involved in changing openings, instead putting the focus on managing your existing repertoire more efficiently.
1. Create your own database: You put in tournament games, online games with a decent time control and correspondence games.
2. Select critical positions: Whatever opening systems you play, you can find some middle game positions that occur in your games the most and put them into different categories. For example winning positions, losing ones and those which are difficult to handle or uncertain.
3. Use the computer as playing partner: I am not big fan of using a computer for chess preparation but here you can use computers in more sensible way. First of you can select levels which you want to play against then play your selected positions as black and white in order to grasp the ideas and spot out tactical possibilities.
4. Using the database: Once you have plenty of experience in playing the selected positions, now it’s time to see how the experts play them. You simply search positions using any chess database and can go through the games.
The whole process is nothing but a way working on the selected patterns in more organised way.