Dr.Dave's Brain Sharpening Kit

Sorry if that sounds a bit alarming!  What I mean is, after the summer break, you might find that your usual tactical sharpness has gone a bit rusty. 

To get back to your normal diamond-honed sharpness, you just need you get your eye back in with some practice.

Some things to practice are:

1. The Eight Queens Problem - a great exercise for whole-board awareness - a bit hard to check your solutions yourself, but now there is an Android phone app!
2. Dr.Dave's exercises to practise spotting attacks and defences - again a bit hard to check for yourself, but as long as you're trying it's doing you good.
3. If you can spend a bit of money, I hear Fritz these days will also help you practise spotting attacks and defences.
4. There is the splendid free Chess Tactics Server which will rate your ability to solve tactical positions quickly.  I think that's the original one but there are a few others about now.
5. There are tactics puzzle sets for all sorts of chess software systems.  Some of these are free or offer a free 'taster' version, so no need to hand over lots of cash before you try it.
   
6. If you're up to it: try blindfold chess.  After all, when you analyse, it's not the position in front of you that you are trying to decide about, but one yet to appear!
7. There are old-fashioned things called books which older readers will remember; get hold of any old books on tactics and do them over and over again until you can almost do them at a glance. 
   

I remember a story from Dan Heisman:

“One of the most important ideas involving safety is that basic tactic skills should be used to prevent an opponent’s tactics, not to find winning tactics for oneself!” [or at least - not just that - DR]

"Unfortunately, I have found that this idea is either misunderstood or continues to fly under the radar.

[...]

...a typical 'Class B' student that I had a few years ago. I suggested he start by studying the basic tactics in John Bain’s Chess Tactics for Students, which he subsequently purchased. At the next lesson, he began by politely shoving his copy of the book across the table at me, saying “You’ve got to be kidding. These problems are way too easy for me!”

I proceeded to examine two recent games he had lost, and it turned out that both losses were primarily due to overlooking, and thus allowing, his opponent to play a basic tactic. After the second game, I said “I don’t understand. You said that Chess Tactics for Students was too easy for you, but are you saying that the two tactics that caused your losses in these games were more difficult than the tactics in this book?”

The student stared at me for a few seconds. Then he reached across the table, grabbed the book back, and quietly admitted “I see what you mean.” To be fair, this student’s attitude is typical of most players near his level.

After hearing this story, one could argue that it was not my student’s lack of familiarity with the patterns, but his lack of a Real Chess* thought process that was his main problem. And that could be true – thought process and pattern recognition go hand in hand. But it is also undeniable that the more familiar you are with a pattern, the more you will avoid allowing it for your opponent, no matter how poor your thought process."

* That is - "If I play this move, can I meet all the threats that my opponent can make with their reply?" - DR

http://www.chesscafe.com/text/heisman106.pdf