The right approach to speed chess depends on the goals a player sets for himself. Those serious about playing in classic tournaments should ideally spend at least 60 percent of their playing time on slow chess. Playing too many speed games tends to make one impulsive in classical chess also. Experienced and advanced players can usually shift from one time-control format to another easily but novices and intermediate-level players have to take care to play more slow chess as indicated.
Tal and Fischer are two great speed chess players who were almost addicted to blitz but became World champions under classic time-controls. That is because they were talented and spent many years studying chess seriously and slowly developing habits that enabled them to switch between different time-controls. A great players once gave me a tip which at first seems absurd-play more slow games to become better at speed chess. World Chess Champion Viswanathan Anand advised aspiring champions not to get addicted to internet blitz, but instead to follow live GM games trying to get into the situation of the game mentally.
Though difficult, one can make a determined effort to nail down critical mistakes immediately after a blitz game. Keep a notebook, listing at least some of the mistakes you made on the same day itself. Gradually, a recurring pattern of mistakes is likely to emerge pointing to some weakness in your chess. It could be not seeing knight forks. Now, by solving a few knight fork problems each day, the weakness is likely to become a strength-you will be able to execute a few complex knight forks on unwary opponents!
Tactics is of critical importance in speed chess. And of course the way to improve tactical skills is known to everyone- solve as many tactical problems as you can. The most important point to remember is to solve tactics problems straight from the book. By doing this, your visualization ability is enhanced. A Course in Chess Tactics by Dejan Bojkov and Vladimir Georgiev is ideal as a textbook for tactics because it covers the most important aspects of how the tactics work and how to spot each theme in your games. Work through this book slowly and solve the problems with a chess clock giving yourself say 5-15 minutes for each to ensure disciplined thinking mimicking what one has to do over the chess board. Another great book for tactics-training is The Giant Chess Puzzle Book by Zenon Franco. There are 1001 problems in the book ranging from easy to extremely difficult. Do not ignore the simple problems because that is the foundation on which the complex ones are built.
Speed chess is a good way to get a good grasp of the move orders of your openings. One key benefit of speed chess is the variety of games played because you are playing so many more games covering many openings within a short time-frame.
Endgame skills are critical in speed games to convert advantage to victory or to defend a weak position. Apart from thinking over mistakes committed in a blitz game one can keep a record of it in a notebook which can be referred to later to find out what to study in a good endgame book. One comprehensive reference book that explains concepts clearly is Silman’s Complete Endgame Course.
Improving your understanding of every phase of the game will definitely improve your speed chess. An excellent book covering the entire spectrum of chess-from play in the center to endgames to developing an opening repertoire, in one book is Lars Bo Hansen’s ‘How chess games are Won and Lost.’
In playing speed chess two important points are to be kept in mind. One, to stay calm and focused on the position whether or not you are up as winning a ‘won’ game is not easy with short time-controls. Two, not to play on and on after one is tired especially if one is on a losing streak. That is self-defeating behavior, if it becomes a habit.