The U.S. Army has developed a rapid way of noting new combat techniques used by the enemy, and getting that information, along with successful ways to cope with the enemy practices, back to units preparing to head for Iraq or Afghanistan. This is done when each combat unit, headed for Iraq or Afghanistan, gets its month of training. There is always emphasis on how the enemy is currently fighting. The training is carried out with troops using lasers attached to their weapons, and laser detectors attached to their clothing. Thus if they are "hit" by the enemy, they know they are out of the fight. In addition, each soldier carries a transponder, which records their position throughout the exercise. Thus after each training exercise, the instructors can show where everyone was, and point out who was not where they were supposed to be. These post-exercise briefings are often the most valuable part of the training, since it's what you don't know, or do right, that is most likely to get you killed. These training exercises also use American troops dressed and trained to operate like the enemy. There are also civilians, who speak the language of the combat zone the troops are headed for, and trained to do role playing exercises with the troops, to give them a realistic taste what they will be facing for a year.
For the infantry, it's not enough to know your own combat techniques. The more you know about how the enemy operates, the easier it is to negate their techniques and defeat them. In the last century, armies have sought to distribute knowledge of enemy techniques to their own troops as quickly as possible, especially to new troops or units entering combat for the first time. Currently, the U.S. Army and Marines gather data on enemy techniques and get it distributed very quickly, using Internet tools the troops are comfortable with. But the information also goes back to the United States, and other areas where U.S. combat troops are stationed, so everyone can stay current. Thus if a Taliban unit employs a new combat technique, they have to assume that all American (and NATO) troops in Afghanistan will know about that trick within days, if not hours. In effect, the foreign troops have better knowledge of how the various Taliban contingents fight, than the Taliban themselves (who don't have as effective a system for passing around combat knowledge).
This sort of thing has been increasingly used over the past century. During World War I, when the U.S. entered the war in 1917, combat experienced French and British officers and NCOs went to the United States to help train American troops to fight the Germans. In World War II, the same technique was used, although in this case, American liaison officers were working closely with the British before the U.S. entered the war in late 1941. After that, the U.S. got information on the Germans from the Russians as well, and prepared a series of training manuals (what were constantly updated) for new troops. At the front, intelligence officers collected information on new enemy techniques, and distributed printed (usually one page) lists of these items for distribution to all units currently in combat.
These World War II techniques were used in Korea and Vietnam. But in the 1980s, the army changed the way they handled this knowledge, and set up a "Lessons Learned" operation. CALL (Center for Army Lessons Learned) proceeded to capture lots of combat experience from Vietnam, Korea, Vietnam, and even earlier. The CALL researchers soon noted reoccurring patterns, certain ideas and concepts that kept getting reinvented. Alas, the CALL database is only available to military personnel (to prevent the enemy from knowing which of their tricks we are on to.) But because of things like CALL, and rapid distribution of what the enemy is up to, the troops are on to a lot of enemy ideas, concepts and tactics, as well as how to deal with them, before they get into combat. This does morale and confidence a lot of good, because it works.