Practice important and significant tactics

As the saying goes, "Chess is 99% tactics."  Practicing tactics is probably the single best way to improve your practical results.  Try to spend at least a little time everyday solving tactical exercises, even if you only have time for a few.  Ideally, spend about a half an hour or so per day.  The way many trainers see it, tactical skill involves at least two things: pattern recognition and calculation skill.  You can develop your ability to recognize tactical patterns by regularly reviewing the same small set of tactical examples; to that end, some USA trainers recommend that you re-read Seirawan’s Winning Chess Tactics on a regular basis.  You can develop your skill at calculating by regularly tackling a wider variety of new and diverse exercises; to that end, it is recommended that you get one or more collections of tactics and combinations.